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THE DANFOSS JOURNAL. Published by Danfoss A/S, DK-6430 Nordborg, Denmark. Telephone: +45 7488 2222. Telefax: +45 7449 0949. E-mail: [email protected] Telex: 50599 danfss dk. Visit us on the Internet: Editor-in-Chief: Finn Märcher. Copyright: The publishers. Print: © Danfoss A/S 00.11.APH.FW.R.

AUTOMATIC CONTROLS DESIGN AND PRACTICE. 55ND YEAR NO. 4-2000 ISSN 0011-6076 Also published in Danish, German, Spanish, Swedish, Dutch, French, Italian, Finnish, Russian, Polish, Czech, Chinese and Japanese. Reproduction of articles is usually permitted subject to acknowledgement. The editors accept no responsibility for possible errors in The Danfoss Journal. All trademarks in this material are property of the respective companies. Danfoss and the Danfoss logotype are trademarks of Danfoss A/S. All rights reserved. Some Danfoss products mentioned in this publication may not be available in all countries.

Environmentally friendly waste handling ­ drinking water instead of oil

There, behind the Citygross supermarket in Mantorp, Sweden, stands a machine, the first of its kind in the world. It compresses waste and is driven by ordinary drinking water.

Commercial compressors designed for high ambient temperature

Danfoss Maneurop is now represented in more than 100 countries, with production plants in Europe and the United States.

Flexible solution for a flexible material

VLT® 5000 frequency converter with a built-in SyncPos controller for film wrapper applications.

The world's smallest softstarter

Here it is ­ the world's smallest softstarter! MCI 3 is the latest innovation in the CI-tronicTM product range. The module size of only 22.5 mm [0.9 inch] is half the space taken up by corresponding softstarters on the market.

New regulators for industrial refrigeration

Paint robot optimised

MASSFLO® mass flowmeter, series MASS 6000, controls a robot spray gun.

Market introduction of the new current-limiting circuit breaker range at the beginning of 2001

The front page shows the Parliament Building in Kuwait City, designed by the Danish architect Jørn Utzon (famous for his Sydney Opera House). At the other end of the Persian Gulf ­ in the United Arab Emirates ­ Danfoss has established its own support centre. See article on page 4.

Danfoss is a global company, created by the efforts of committed people respecting local values, mastering advanced technology and with a high degree of environmental consciousness. We are proud to present our products and services, which are for vital functions in our homes, at workplaces, in the industry and throughout the environment.



Environmentally friendly waste handling ­ drinking water instead of oil

By Alan Mortensen Marketing Planning. WATER HYDRAULICS Based on an article in the Swedish newspaper "Östgöta Correspondenten", 11 March 2000 by Maria Hovberg.

Environmentally friendly machinery It is not just the compression process that is environmentally friendly. The machine that presses down cardboard and vegetable scrap is driven by water ­ ordinary drinking water. "Yes, the motor uses electricity, but the hydraulic system operates on water rather than oil," explains Lars Lindh from Danfoss who together with ALFA Försäljnings AB built the system. First in the world Several companies in Sweden as well as the rest of Europe are busy with water hydraulics. In 1994 Danfoss became the first company in the world to produce an entire system using this technology and the rumbling press behind Citygross is the first stationary waste compressor in the world to incorporate the technology. Advantages These new systems are constructed using stainless steel and plastic materials able to withstand very high pressures without the need for lubrication. The advantages of water are many. For example, oil leakage entails expensive cleaning routines and can pollute a whole area. But if water leaks out it merely returns to the place it came from ­ nature. Water is also cheap and need not be changed. The pressure in the system kills bacteria and therefore the water never becomes rancid. According to Lars Lindh, below-zero temperatures

at the supermarket loading ramp is not a problem either. "With outdoor applications we add a glucose mixture to the water, i.e. ordinary sugar. This is completely harmless and stops the water from freezing." Expensive technology There is one disadvantage with water hydraulics: it is expensive. "A water system is probably around 20% more expensive than a traditional oil system. But in the long run the extra cost is outweighed by the much more economical operation," continues Lars Lindh. However, the high price of the investment did not scare off the Citygross discount store. The manager, Mikael Lindahl, has no doubts about it, "We always consider the environment and we begin out at the back rather than hang banners at the front. And the system we bought was certainly a good investment." Because water hydraulics can be used everywhere traditional oil systems are used today, Lars Lindh is convinced that there is a future for this new development of an old invention. "All right, it's expensive. But is the environment not worth paying for? We have to think of the next generation." For further information, please contact: Torben G. Pedersen, telephone: +45 7488 5272, fax: +45 7445 3831, e-mail: [email protected] At the moment, Nessie® water hydraulic components are available in Western Europe and the U.S.A.

Nessie® is a registered trademark of Danfoss A/S.

There, behind the Citygross supermarket in Mantorp, Sweden, stands a machine, the first of its kind in the world. It compresses waste and is driven by ordinary drinking water. Danfoss' large stake in the water hydraulics area has again made its presence felt in practice. Sounds of machinery hard at work come from the hydraulic press just by the blue waste containers at the loading ramp behind the food hall. Here, great quantities of waste are compressed. Just the corrugated cardboard that Citygross discards amounts to four tons [5 tonnes] every two weeks. "If we didn't compress the waste there would only be space for about 300 kg [660 lb] in a container like this," says John Ilar from the haulage contractors, Östgötafrakt, who transport waste from the food hall. "In this way we can squeeze in four tons and save a great deal of road travel ­ and that's good for the environment.

The container with the first water-hydraulic waste press in the world.




Commercial compressors designed for high ambient temperature

By Bhupinder Godara Application Engineering Danfoss Maneurop, Middle East COMPRESSORS FOR AIR CONDITIONING AND REFRIGERATION

Thus the same compressor can be used for air conditioning as well as in chilling applications. For freezer applications, the LTZ range of compressors covers evaporating temperatures from -45°C to -20°C. These compressors have a significantly higher capability to withstand refrigerant flood-back. This is due to a higher internal shell volume which enables the compressor to also function as an accumulator. The compressor motor is 100 per cent suction-gas-cooled. This eliminates the need for air circulation around the compressor and offers more flexibility in locating the compressor. The compressor can be enclosed in an acoustic hood to further reduce its operating noise level. The motor winding insulation is class 'F', as compared to the class 'B' insulation found in other equivalent products on the market. Class 'F' insulation gives the motor better protection against burnout. The permissible motor winding temperature is 155°C for class 'F' insulation as against 125°C for class 'B' insulation.

From air conditioning to refrigeration ­ in just a few years Danfoss Maneurop (the Commercial Compressors Division in the Danfoss Group) has proven its capacity to satisfy the real expectations of the market. Danfoss Maneurop has established additional facilities and is now represented in more than 100 countries and with three production plants in Europe and the United States, and logistics centres, the main regions of the world are covered. The most recent addition to this list of customer support centres is the Jebel Ali Logistics platform in the United Arab Emirates which was inaugurated in October 1999. Not only does this centre offer off-the-shelf availability but its presence confirms the fact that the products it deals with are suitable for operation in one of the hottest climates in the world. Danfoss Maneurop has three product ranges for commercial refrigeration and air conditioning: Maneurop reciprocating compressors Renowned for their reliability and exceptional suitability in the Middle East environment, Maneurop reciprocating compressors need no introduction. Over the last 25 years they have become the reference brand for refrigeration, air conditioning and industrial cooling processes. The MT compressors are renowned all over the world for their almost legendary reliability and cover all requirements in the 1.5 to 26 hp range. Danfoss Maneurop products have been developed even further and offer even greater efficiency and reliability when operating with the new refrigerants. One more step in protecting the ozone layer. The MT series covers a wide evaporating temperature range extending from -25°C to +15°C.

Danfoss Maneurop compressors offer the highest limit on maximum operating condensing temperature, i.e. + 68°C. The advantages of class 'F' insulation and 100 per cent suction gas cooling make the compressors particularly reliable in high ambient temperatures. The maximum condensing temperature is one of the key parameters in determining compressor suitability in high ambient temperatures. The difference between condensing temperature and ambient temperature is the main factor in good heat dissipation. When the ambient temperature rises, the condensing temperature also rises to sustain heat exchange. The upper condensing temperature limit of these compressors thus significantly enhances their

Internal motor protector

High level suction inlet

Internal pressure relief valve

100% gas-cooled motor

Superstrong epoxy-coated motor winding

PTC crankcase heater Large shell volume Impact-resistant valves Discharge line sump heater Oil sight glass






reliability when operating in high ambient temperatures. Blue Star condensing units From commercial refrigeration applications to industrial process cooling systems, the Blue Star condensing units provide the most complete solution for the "hermetic" market. Built-in reliability and safety ­ Fitted with Maneurop hermetic compressors for R 22, (or) R 134a, R 404A/R 507 refrigerants. ­ Condenser fan motors suitable for high ambient temperature. ­ Receivers with a maximum operating pressure of 33 bar (485 psig). ­ Sight glass fitted on all compressors for checking the oil level, oil quality and refrigerant migration. Maximum efficiency Advanced condenser technology with rifled copper tubing and enhanced aluminium louvered fins help reduce the air flow velocity and reduce operating noise levels. Easy installation Blue Star's "all in one" hermetic unit on a compact base frame fulfils installers' requirements and emphasises serviceability and safety. The units: ­ are equipped with service valves and extended copper ends, ­ are factory pre-wired, and have a terminal box that simplifies field installation and eliminates miswiring, ­ have pressure ports and electrical test points for easier start-up and commissioning. The "zero leak" objective The entire system is checked for leaks with a helium mass spectrometer. Factory tested Each and every unit is connected and tested under operating conditions. A dry holding charge (neutral gas) is introduced to maintain system cleanliness until the Blue Star unit is installed. These units are available in five different voltage codes (i.e.: combination of compressor and fan voltages), for 50 Hz as well as 60 Hz. Performer scroll compressors In water chillers, self-contained air conditioning units, split systems, central air handling units, heat pumps, Performer scroll compressors are increasing their lead in commercial applications within the range 7 to 100 ton. With its completely new concept and innovative design, Performer is truly ushering in a new era where the demanding market of air conditioning is concerned. The scroll compressors are suitable for environmentally

friendly R 407C, R 134a and also for R 22. The present range extends from 7 to 15 hp for a single compressor and from 15 hp to 30 hp for tandem units. Tandem units consist of two single compressors connected in parallel and mounted on a frame. Gas flow path in Performer Suction gas enters the compressor at the suction connection. The gas flows around the motor, entering the housing through bottom openings. All gas passes through the electric motor, ensuring full motor cooling in all applications. After leaving the motor, the gas enters the scroll elements for compression. Performer makes the difference Dynamic contact between the scrolls is through two patented floating seals that give perfect axial tightness (as shown in the figure) and reduce mechanical stresses and strains. Additionally, extremely accurate, modern machining technologies ensure that a simple oil film is all that is necessary to fully seal the scroll

ing parts. This minimises friction, increases compressor volumetric efficiency, reduces vibration, guarantees compressor performance and extends service life. Performer scroll compressors have a large oil reserve and a greater refrigerant charge capacity than most other compressor designs. Performer proves its superiority with longer service life in every type of application from the simplest to the most complex. These compressors are available with different motor voltages, i.e. 400 V/3/50 Hz, 460 V/3/60 Hz, 230 V/3/50 Hz, 230 V/3/60 Hz & 380 V/3/60 Hz. Danfoss Commercial Compressor products perform superbly in the most demanding environmental conditions. For further information, please contact: Danfoss Maneurop Commercial Compressors, tel.: +33 4 7400 2829, fax: +33 4 7400 5244 or e-mail: [email protected]

Reverse rotation protection Discharge check valve Discharge port

Orbiting scroll

Oldham coupling

Discharge connection Stationary scroll

Multiple knockout connecting box Upper bearing, shaft and counterweight

Motor protection Shielded motor 100% gas-cooled Oil sight glass

Lower bearing and oil pump

Suction connection Rotolock brazed

flanks, eliminating contact between mov-




Flexible solution for a flexible material

By Ole Gernhøfer Global Team Manager ELECTRICAL DRIVES AND CONTROLS

Dutch equipment manufacturer Lareka utilises the benefits of the Danfoss VLT® 5000 frequency converter with a builtin SyncPos controller for a film wrapper application. When you print messages like prices, bar codes or advertising slogans on the film used for wrapping cigarette packets, you definitely want those messages to appear in the exact position ­ and not turn around corners. Simple as it sounds, this detail represents a major challenge to the manufacturers of cigarette packaging machines: plastic film is an extremely flexible material and positional tolerances can be several millimetres, which is quite a distance on a cigarette packet. As an experienced manufacturer of equipment, particularly for the tobacco industry, Lareka Machines/ITM b.v., situated near Eindhoven, Holland, has been striving to find an ideal packaging system for years, but the optimum solution was not developed until a VLT® 5000 frequency converter with a built-in SyncPos controller was included in the design. Jos Willemsen, section leader, electronics, explains: "Formerly, we used to develop purely mechanical devices based, typically, on a planet wheel controlled by a phase shift system with a stepmotor. However, such applications were complicated and had to be tailor-made for each machine type. The cost was enormous." Lower price with Danfoss Looking for alternatives for a new packaging system, the development team at Lareka had their attention drawn by their electronics supplier to the SyncPos option of the VLT 5000 frequency converter. The frequency converter was known to the company, but had not been used for positioning purposes. "Actually, we had considered using a servo drive, but the VLT drive offered the same functions at a much lower price," Jos Willemsen adds.

Lareka's new film wrapping machine for cigarette packets.

Uncomplicated design Price aside, Jos Willemsen mentions extensive flexibility as the paramount benefit of the SyncPos-based system and points to the following characteristics: ­ The system is able to operate with different types of film wrapping machines and is also used for synchronising the filling of twist tobacco into bags on another Lareka machine. ­ When changing to a different packet size the cutting length can be changed right away. ­ When handling unprinted film not requiring positioning but merely accurate cutting length, resetting is just a matter of pushing a button. ­ The system can be retrofitted on existing equipment without dismantling. All settings are made in advance (without using a PLC) leaving only adjustment of the cutting length to be performed on the spot ­ simply by using the frequency converter interface. "The flexibility of the new application is due to the uncomplicated design. All you need is a motor and a drive. That really

has removed heavy burdens from our shoulders," Jos Willemsen says. Time savings are a tangible benefit of the overall flexibility ­ both for Lareka and its customers. "Retrofitting takes one person three days. This is extremely fast ­ and greatly appreciated by our customers who cannot afford much downtime," Jos Willemsen maintains. Integrated quality control Simple design and flexibility have, however, not been accomplished at the expense of accuracy. A required tolerance of 1 millimetre [0.04 inch] is maintained. Furthermore, quality control is an integrated part of the wrapping process: ­ If the film is not properly positioned, the VLT frequency converter sends a signal to the external control system. Simultaneously, the packet concerned is rejected. When a given number of packets have been rejected the machine stops. ­ Missing cutting marks on the film, or photocell faults, also stop the machine.




Fig.1 The operational principle of the film wrapper as sketched by Jos Willemsen in the specification phase of the project.

So far, Lareka has supplied 16 of the new SyncPos-based systems, but Jos Willemsen does not try to conceal the fact that there have been difficulties on the way ­ equally shared with Lareka's system integrator, ARMAC. "We have been pioneers, so we had to learn a few lessons. But Danfoss was there all the way to back us up," he recalls. Today, Lareka and Jos Willemsen see their efforts rewarded in the form of potential for growth. With the flexibility achieved they have a favourable starting point for meeting almost unlimited requirements in wrapping chocolates, candy, CDs, pencils, and many other items. Wrapping cigarette packets ­ a system description Lareka's printed film wrapping system, featuring a VLT 5000 frequency converter with a built-in SyncPos controller, is sketched in figure 1: The system basically consists of a wrapping machine (1) and a system for delivering the film (2) along with the seal tape (3). ­ The film feeder runs continuously to maintain positive and stable film tension during operation so that film slack does not appear. ­ The feeder (secondary unit) runs synchronised with the wrapping machine (primary unit) so that an equal length of film is fed into the wrapping machine for each packet at varying machine speeds. The tolerance on length is ±1 mm [0.04 inch]. ­ For a given position of the wrapping machine the feeder maintains a fixed position in accordance with the indicating marks on the foil. There is one mark for each piece of foil. The fixed position is maintained within a tolerance of ±1 mm [0.04 inch].

­ A special function takes care of feeding in a new roll of film. It performs a "synchronised" stop according to the position of the wrapping machine and the film marks and so maintains the fixed relative position described above. The accuracy of the synchronisation process is monitored by an external control system which is alerted if synchronisation is not within specific tolerances. The wrapping machine motor is equipped with an optical encoder and performs one revolution per packet. Consequently, the zero pulse from the encoder is used as a governing marker signal. Another application ­ another drive With a comprehensive range of products, Lareka gains other benefits from the Danfoss VLT frequency converter range. For example, the newly released VLT 2800 converter has been successfully used in teartape unwinder applications. The frequency converter controls the speed of the machine. It operates with an analog proximity switch (4-20 mA) mounted on an arm that registers the speed. The tape feed is controlled accordingly. "The speed-independent and precise stopping offered by the VLT 2800 was an important argument in choosing this solution. But the compact size and competitive price were even more decisive," says Jos Willemsen. He notes that Lareka has already shipped 50 teartape unwinders and adds that the VLT 2800 frequency converter was also included in the recent development of a new candy wrapping machine.

For further information, please contact: Ole Gernhøfer, tel.: +45 7488 3073, fax: +45 7465 2580 or e-mail: ole_gernhø[email protected]

VLT® is a registered trademark of Danfoss A/S.

VLT® 5000 frequency converters with built-in SyncPos controller in the control panel.

Positive and stable film tension is decisive for continuous operation.

Jos Willemsen with printed film ­ cut at a speed of 400 pieces per minute.

VLT® 2800 frequency converter for speed control in a teartape unwinder application




The world's smallest softstarter


Here it is ­ the world's smallest softstarter! MCI 3 is the latest innovation in the CI-tronicTM product range. The module size of only 22.5 mm [0.9 inch] is half the space taken up by corresponding softstarters on the market. MCI 3 is a new, effective and extraordinarily compact unit for reducing undesired high starting torque and high inrush current on three-phase motors with a rating of 3 A (AC-3). MCI 3 is now being offered together with the other softstarters from the CI-tronicTM product range; a range which also includes MCI 15 and MCI 25, etc. The latter types have already gained a firm place on the market and have benefited many customers. When an asynchronous motor is started direct, it pulls a high starting current and generates high torque when it is cut in. The high inrush current ­ 5 to 8 times the rated current on direct starting ­ often gives short-lived but disturbing voltage drops on the supply network. The high starting torque causes unnecessary wear in other components such as chains and V-belts, which in turn means increased maintenance costs. Familiar methods There are several methods of reducing starting torque and starting current. The most well-known is probably star-delta start which is built up around a number of electromechanical contactors. The motor is started in star connection and, depending on the application, several seconds pass before the motor changes over to delta connection. The disadvantage of star-delta start is the low starting torque it produces, which means that it cannot be used in all applications. In addition, the motor pulls a powerful current that creates high torque at the moment the changeover to delta connection occurs ­ almost as if there had been a direct start. Another well-known method is autotransformer start. Here too motor start is accompanied by jerks and the same disadvantages as with star-delta start.

Electronic softstart Electronic softstart and softstop gradually change the motor voltage when the motor is started or stopped. The advantage of using electronic softstart is that starting torque can be reduced to an absolute minimum and the inrush current can be reduced by up to 50%. In pump applications softstop can also be MCI 3

an advantage, in that liquid hammer can be completely avoided. Because of its size, MCI 3 is especially attractive when there is need for the softstart and softstop of conveyors. These are often driven by gearmotors with a rating of less than 3 A, therefore regulated starting and stopping is a decided advantage, especially if heavy objects are to be transported. MCI 15

»K 2 O


Motor rating Max. rated current Module size Ramp up Ramp down

0.1-1.5 kW 3A 22,5 mm 0.5-10 seconds 0.5-10 seconds

0.1-7.5 kW 15 A 45 mm 0.5-10 seconds 0.5-10 seconds


»Kick start« 200 ms Of max. torque 0% Inital torque up to 85% of nominal torque Time


Like the other softstarters in the CI-tronic range ­ MCI 15, MCI 25 and MCI 25B ­ MCI 3 is just as easy to select and install as an electromechanical contactor. Or in other words, it offers new and advanced technology incorporated in a particularly user-friendly mechanical/electronic unit. MCI 25 is also available in a version with a built-in electronic switch for the external bypass of operating current. The CItronic range is wide and includes units that will start and stop motors with ratings of up to 30 A or 15 kW [20 hp] (3×400 V). Customers who have chosen CI-tronicTM Lind Jensens Maskinfabrik A/S in Denmark use type MCI softstarters. The company manufactures pumps and agitators for liquid manure tanks. The pumps are immersion units that are installed in the bottom of tanks to pump the manure up. The liquid manure precipitates while being stored in the tank, therefore it is necessary to use an agitator. The reason why softstart has been chosen for the pump motor is the need to reduce the starting current. Softstart has also been chosen for the agitator not only to reduce the motor starting current, but to avoid high starting torque and the consequential mechanical wear.

The company previously used start-delta starters, but since MCI units almost completely eliminate voltage drop on cutin, and because they are very much smaller, electronic softstart was chosen instead. An OEM producer of air conditioning plants in Malaysia also chose to use MCI softstarters. In such plants the compressor unit and electrical controls are located outside the building while a number of evaporators are installed in the rooms where air conditioning is required. An MCI is used to softstart the compressor and so meet the requirement for minimum current surge on compressor start. This customer previously used autotransformer start, but the MCI takes up far less panel mounting space and the company could also see the advantages of being able to offer customers the advanced technology incorporated in the softstarters. MCI 3 softstarter In spite of its small size, the MCI 3 occupies a natural place in the CI-tronic range of softstarters. Like the other MCI units, the MCI 3 has adjustable start and stop setting from 0-10 seconds. If the application demands a certain degree of starting

torque, this can be set between 0 and 85%. Furthermore, it is possible to select booststart, i.e. maimum torque for 200 ms. With selectable ramp times, starting torque adjustment and booststart, the MCI 3 is so flexible that it can be adapted to suit by far the most motors rated at up to 3 A. Two LEDs indicate the operating condition, including when phase dropout occurs. The universal control circuit can be connected to voltages of 24-480 V a.c. / d.c. and there is automatic adaptation to 50 / 60 Hz. Other units in the CI-tronicTM range In addition to type MCI softstarters, the CI-tronic range of motor controls includes TCI starting torque limiters, RCI reversing contactors and MCI DOL electronic contactors for direct start. All in all a very wide assortment of electronic motor control products. For further information, please contact: Michael Quitzau, tel.: +45 7488 4512, fax: +45 7488 3358, e-mail: [email protected]

CI-tronicTM is a registered trademark of Danfoss A/S.

Motor torque (Voltage) 100%

Rampe up 0.5-10 s

Rampe down 0.5-10 s

MCI 25


MCI 25 I-O

0.1-11 kW 25 A 90 mm 0.5-10 seconds 0.5-10 seconds

0.1-11 kW 25 A 90 mm 0-10 seconds Braking torque adjustable

0.1-15 kW (bypassed) 30 A (bypassed) 90 mm 0.5-20 seconds 0.5-20 seconds




EKC 361 and EKC 366 ­ new regulators for industrial refrigeration


EKC 366 EKC 366 replaces EKA 46 and in addition to the basic functions also incorporates a number of improvements. EKC 366 and PM/CVQ together offer users a degree of access which means that they themselves are able to set up and operate the PM/CVQ and in so doing establish regulation algorithms in main control systems. See fig. 2. Temperature regulation with evaporating pressure regulation On evaporators where the temperature of the cooled medium is to be regulated very accurately, the process is typically performed using evaporating pressure regulation. The choice of regulating valve for this type of application is usually between: ­ motorised valves ­ for example an MRV from Danfoss Industrial Refrigeration, ­ pilot-operated, pressure-dependent valves ­ for example PM with CVQ from Danfoss Industrial Refrigeration. Motorised valves A very small pressure drop across the valve is sufficient to fully open a motorised valve. This is very important, especially in systems with very low suction pressure (< -35°C evaporating temperature).

The operation of a motorised valve as the regulating organ is easy to grasp. Typically, it is operated with an input signal of 4-20 mA or 0-10 V. This means that in some cases the selection of a motorised valve is based on what might be called fundamental or practical knowledge rather than on a more technically correct evaluation. Pilot-operated, pressure-dependent valves A PM main valve with a pressure-dependent pilot valve makes up a unique system for applications where the accurate temperature control of cooled medium is required. One advantage offered by the system is that PM/CVQ incorporates a mechanical pressure regulator which makes rapid compensations for pressure variations on the discharge side of the PM valve in relation to the set reference pressure on the inlet side. Compensation for changes in pressure on the discharge side of the PM valve or for load changes on the evaporator side is very rapid, so that the pressure in the evaporator is constantly brought into line with the set reference pressure. The reference pressure is regulated with a CVQ pilot valve via an EKC 361 or EKC 366, based on the measured temperature of the medium. In addition, the EKC 361/366 can be used to protect the plant from impermissibly low evaporating temperatures. Despite the benefits of this solution, in practical terms it has proved to be difficult to explain to customers why it gives optimum regulation. Especially in situations where customers themselves wish to operate a PM/CVQ from their own PLC system, relatively many questions have been asked about the theory behind it and about the way it actually operates. From a practical point of view, EKC 361 and EKC 366 make it far easier to set up and operate CVQ and thus PM. The PM/CVQ system is often compared with a motorised valve system, which cannot be done because, basically, a PM/CVQ valve is pressure-dependent whereas a motorised valve is pressureindependent. It is very important to distinguish between the two different concepts. Pressure-dependent versus pressureindependent regulating valves In describing pressure-dependent and pressure-independent regulating valves used for temperature regulation it is important to note the physical relationship between pressure and temperature. Pressure changes occur rapidly. Temperature changes occur slowly.

In a refrigeration plant where accurate temperature regulation is required it is not just important to look at the temperature. It is also essential to focus on the evaporating pressure, a factor often overlooked. For many years Danfoss has marketed the PM/CVQ system as the optimum, a system which takes account of pressuredependence as a parameter in the regulation of temperature in a refrigeration plant. Danfoss Industrial Refrigeration is now introducing a series of new regulators, EKC 361 and EKC 366 for the PM/CVQ system, which reflects the significantly greater recognition of the effect pressure changes have on accurate temperature regulation. EKC 361 and EKC 366 belong to the EKC product series, which means that a wellknown concept is being taken further. EKC 361/366 have an LED display and are based on digital microprocessor technology. EKC 361/366 are fully compatible with existing regulators both functionally and as far as connections are concerned. That is to say, in the case of upgrading an existing plant for EKC 361/366, there is no need to replace the Pt 1000 sensor, the CVQ or PM valves. EKC 361/366 incorporate the following extra facilities in relation to the regulators they replace. ­ 3-digit LED display with one decimal place ­ 2 pushbuttons to operate the regulator ­ LED to indicate operation ­ Standard AI/AO signals: 0/4-20 mA ­ EKA 173 communication module can be fitted (option) ­ LON protocol ­ Improved diagnostic facilities. EKC 361 EKC 361 replaces EKS 61 and in addition to the basic functions offers many improvements. The combination of EKC 361 and PM/CVQ is complete and unique, offering the user an easily understandable and simple-tooperate package for a complex regulation task. See fig. 1.





CVQ Evaporator AKS 21 Pt-1000 Compressor EKC 61 Control AKA 243 Gateway

of load changes. Thus, PM/CVQ and EKC 361 are able to regulate the temperature of a medium very accurately. See fig. 4. Several obvious advantages are offered by using PM/CVQ and EKC 361/366. The regulating system will accurately and constantly ensure that the evaporating temperature is kept so close to the temperature of the medium that the capacity requirement is just covered all the time.

PM valve

Fig. 1 PCL CVQ

Compressor AKS 21 Pt-1000 PM valve EKC 61 Control AKA 243 Gateway

Fig. 2


The small temperature difference between the temperature of the medium and the evaporating temperature gives the least possible drying out of refrigerated goods ­ and the tendency for frost to form on the evaporator also becomes less. A further advantage is operation with optimum energy consumption since evaporating temperature is always held at the highest possible level. EKC 361 and EKC 366 Now, with EKC 361/366, there are improved possibilities of making adaptations to suit a main control concept for industrial refrigeration plant. Different forms of process refrigeration often involve different pull-down sequences, i.e. different temperature sequences. Override functions based on standard signals 0/4-20 mA/0/2-10 V, can be accurately set to suit the temperature range of the application and thus ensure a high degree of flexibility in connection with the exchange of signals between EKC 361/ 366 and the main control system. With EKA 173 (option) mounted, EKC 361/366 becomes a fully-fledged member of the ADAP-KOOL® product family and opens the way to countless possibilities already familiar to many ADAP-KOOL users, for example: ­ Full operation of EKC 361/366 from a PC with AKM installed ­ Trend graphs on PC ­ Data collection via AKA 243 gateway ­ Call-up to EKC 361/366 via modem. EKC 361 and EKC 366 now provide much better possibilities of being able to offer optimum systems to the industrial refrigeration sector, both on the refrigeration technology and on the electronics side. For further information, please contact: Danfoss Industrial Refrigeration. Kurt M. Sand, Product Manager, tel.: +45 8738 9625, e-mail: [email protected]

ADAP-KOOL® is a registered trademark of Danfoss A/S.

Compressor EKC 61 Control


Motor valve Evaporator


Fig. 3


Compressor EKC 61 Control Evaporator Fig. 4


PM valve


Compressor capacity is increased at point A and reduced at point B.

A typical refrigeration plant contains several compressors, screw and/or piston types, with capacity regulation. This means that momentary pressure changes will occur in the suction line. The pressure changes will thus also be present in the regulating organ in the suction line. When a motorised valve is used, such pressure changes are transferred to the evaporator and change the boiling point of the refrigerant and with it the temperature in the evaporator. Because it is pressureindependent, a motorised valve cannot make rapid compensation for pressure change. Only when the temperature sensor has registered the temperature change can the regulator intervene. A regulating system with a motorised valve cannot accurately regulate and maintain temperature, in that temperature changes occur slowly in relation to pressure changes. See fig. 3.

The picture with PM/CVQ and EKC 361 as the regulator is quite different. It is able to handle the rapid pressure changes caused by compressor capacity regulation. PM/CVQ remains in pressure balance the whole time to maintain the necessary evaporating pressure. When a pressure change occurs in the system, PM/CVQ quickly establishes a new pressure balance to maintain evaporating pressure. This compensation for pressure changes is performed purely mechanically; the PM valve sets itself to suit the new pressure balance. See fig. 4. The function of the CVQ pilot valve is to adjust the reference for this pressure balance. The reference can only be adjusted through the EKC 361 regulator when a temperature change is registered by the AKS 21 sensor. In this way the system is able to control both the rapid pressure changes that occur as a result of capacity regulation, and the temperature changes arising as a consequence




Paint robot optimised by cutting down response time to a third

By Anders Leidermark Product Manager INSTRUMENTATION

The spray gun moves at a speed of 1,300 mm per second. With a frame size of 400 mm this gives a processing time of 308 milliseconds per frame. The flowmeter measures actual flow within this time frame of 308 milliseconds. The flow value is passed on to the paint robot control circuit which keeps the flow at a constant pre-set quantity ­ in this application 100 g per minute. When a frame painting operation has been completed the paint gun moves to a new start position within 400 ­ 500 milliseconds. From here a new painting procedure starts. In practice this sequence results in very rapid intermittent flow. In addition to being part of a control parameter for the paint gun, the MASS 6000 measures and sums the quantity of paint used per frame in a certain period of time, i.e. MASS 6000 has a built-in summation counter. Such data are used in connection with documentation in accordance with ISO 9001. The results The three technologies involved in the test at ABB Flexible Automation produced different reactions to the requirements: ­ Mechanical flowmeter. With a response time of 60-70 milliseconds this meter had no problems with the critical 308 Intermittent flow MASS 6000 . . . . . . . . . . . . 50.82 grams Balance . . . . . . . . . . . . . . . 50.70 grams

With the new MASSFLO® mass flowmeter, type MASS 6000 from Danfoss controlling a robot spray gun, ABB Flexible Automation enhances operational speed, improves accuracy and reduces paint consumption. When designing industrial robots for the automated painting of components, two parameters are crucial to optimum performance: the speed and the accuracy of paint dosing. Maximum speed increases the flexibility and the profitability of the equipment, while extreme accuracy is a precondition of ensuring finished products of top quality. Until now, dosing has typically been performed by mechanical gearwheel meters. This technology has no problems dealing with the requirement for speed, but gearwheel meters pose a range of problems that restrict the operation of paint robots. Among these are: ­ Insufficient accuracy when the application demands continuous, repetitive dosing in accordance with the original setting. ­ Insufficient resistance to the high water content in modern paints. ­ Sensitivity to particles in the paint that cause wear and tear. These obstacles to optimum operation are well known at ABB Flexible Automation AB, Finishing, in Malmoe, Sweden. This leading manufacturer of paint robots for a variety of industries has strived to combine speed and accuracy in their equipment for many years. With the MASSFLO® mass flowmeter, type MASS 6000 from Danfoss, ABB engineers recently made a breakthrough that outclassed other solutions. The results were documented in a test that included mechanical flowmeters as well as MASS 3000, the predecessor of MASS 6000. The set-up The application in question is a robot with a spray gun which moves up and down to paint components mounted on frames. The frames are continuously brought to the robot by a transportation system.

milliseconds. However, its performance was unsatisfactory due to the drawbacks mentioned above. ­ MASS 3000 coriolis flowmeter from Danfoss. This well-proven meter met all requirements regarding accuracy and robustness, but because of a response time of about 400 milliseconds the actual flow pulses for the controller were too slow (see diagram 1). No less than 200-250 milliseconds are a must for this application. ­ MASS 6000 coriolis flowmeter from Danfoss. This new meter showed a response time of about 150 milliseconds, leaving plenty of time to supply the required flow signal within the given limits (see diagram 2). Thus the MASS 6000 meter performed close to three times faster than the MASS 3000, while still retaining the well-reputed other qualities of MASS 3000. Furthermore, coriolis technology reduces paint consumption by more than 30 percent. In addition to the response test, absolute accuracy was also tested, both with an intermittent "on time" flow of about 0.5 seconds and an "off time" of 0.5 seconds, and with constant flow for 30 seconds. The flow remained at 100 grams per minute. MASS 6000 readings were compared with the summated readings from a precision balance used to weigh paint doses: Constant flow MASS 6000 . . . . . . . . . . . . 50.30 grams Balance . . . . . . . . . . . . . . . 50.20 grams

The robot seen from the rear with a MASSFLO® MASS 6000 flowmeter installed.

The paint spray robot ready for action. The frame shown is for mounting the components concerned.




Tangible benefits The reduction of the response time to one third with MASS 6000 not only ensures fast and accurate operation of the paint spray robot control loop. It also means that ABB Flexible Automation can now limit its purchase of flowmeters for spray robots to one type, i.e. MASS 6000. Last but not least, ABB customers are now assured paint spray robots that are:

Test of response time: MASSFLO® MASS 3000 flowmeter compared to a mechanical flowmeter.

­ Flexible: high performance ensures versatile applicability ­ Profitable ­ Robust and reliable ­ Media independent ­ Paint-saving Summing up the results of equipping the paint spray robots with Danfoss MASSFLO meters, Mr. Alf Andrén, process engineer at ABB Flexible Automation, states: "The test results, comparing the

performance of MASS 3000 and MASS 6000 respectively, clearly show that the new MASS 6000 meter fulfils our requirements regarding operational speed and accuracy in these applications." For further information, please contact: Anders Leidermark, tel.: +46 1428 8742 or e-mail: [email protected]

MASSFLO® is a registered trademark of Danfoss A/S.

Test of response time: MASSFLO® MASS 6000 flowmeter.




New current-limiting circuit breaker range

By Eilert Simonsen Product Manager INDUSTRIAL CONTROLS

in the shortest possible time. The short circuit current increases during the time it takes the circuit breaker to react. Therefore the circuit breaker must, with as short a delay as possible, open the contacts and generate an arc to give effective short-circuit current protection. The parameters having influence on current limitation in a current-limiting circuit breaker are: ­ A short response time (the time from when the short circuit appears to when the circuit breaker begins to break). ­ A short rise time (the time it takes for the circuit breaker contacts to open, and the arc to grow to maximum size). ­ The shortest immobility time (the time from when the arc appears across the contacts until it is extinguished in the arc-extinguishing chamber). ­ A high and constant arc voltage. The latest and most up-to-date technologies associated with research into shortcircuit current and its effects are utilised in the development and design of our new circuit breaker range. With correct design, choice of materials, and geometric form of contacts and arcextinguishing chamber it is possible to

exploit the electrodynamic forces caused by the short-circuit current in such a way that they help to open the contacts and lead the arc voltage out to the arc-extinguishing chamber. The development and design of the new circuit breakers strictly follow the requirements laid down in the international standard on quality systems, ISO 9001. We also observe the requirements of the standard on environmental management, ISO 14001. In this way we ensure environmentally friendly production using environmentally friendly materials. All circuit breakers in the range are CEmarked and tested in accordance with EN 60947-2/IEC 947-2. They have also been approved by UL and CSA for the American and Canadian markets. The circuit breakers have an extremely high break capacity and together with our range of contactors and thermal overload relays, CI-TITM, meet the requirements of coordination types 1 and 2. The new series of circuit breakers is divided into a number of units for different applications. These cover currents from 0.1 A to 45 A and are subdivided into three basic types. These are further divided into a version with standard shortcircuit break capacity and one with high

The purpose of this article is to present our new range of circuit breakers, due to be introduced on the market in the beginning of 2001. A particular application for circuit breakers is the protection of electrical components and installations against short-circuiting. The new range of circuit breakers belongs in the category current-limiting circuit breakers, just like our existing CTI 25 range. Circuit breakers are in two categories: current zero quenching circuit breakers that suppress the short-circuiting current in the zero crossing, and current-limiting circuit breakers that limit the size of the short-circuit current when a short circuit occurs in the circuit. A short circuit can only be limited effectively by a circuit breaker if the arc voltage that appears across the contacts during break rises to a sufficiently high level

Here is a selection of new circuit breakers with accessories, including auxiliary contacts, voltage breakers, undervoltage breakers and rotary knobs.




short circuit break capacity (with built-in current limiter). The one basic type is intended for the short circuit and overload protection of motor installations up to 45 A. In the second basic type the thermal current setting is fixed, intended to give shortcircuit protection in contactor installations of up to 45 A. The third basic type has a high electromagnetic cut-out current and is designed to provide short-circuit and overload protection in transformer installations of up to 32 A. The new range is modular in build-up and all accessories can be mounted on the circuit breakers without the use of tools. Auxiliary and alarm contacts are offered in versions for mounting on the side of circuit breakers or for building into them. Undervoltage breakers and voltage breakers can be mounted on the side of circuit breakers.

Section through a circuit breaker. Note the contact rail form that leads the arc out through the fins and into the arc extinguishing chamber.

Other accessories include current rails for the parallel coupling of several circuit breakers, connection terminals, rotary knobs with lock and caps for terminals and current setting. The range is complete with a lockable door handle and extension, and nameplate, for use in electrical cabinet doors.

All circuit breakers are suitable for mounting on 35 mm DIN rails. They incorporate a test function which simulates thermal trip. There is also an indicator for electromagnetic trip to clearly show that the circuit breaker has switched off because of short circuiting. The position of the rotary knob indicates whether the circuit breaker is off, on, or switched off because of thermal overloading or short circuiting. After thermal or magnetic trip (short circuiting) the rotary knob has to be returned to the off position before the circuit breaker can be switched in again. For further information, please contact: Eilert Simonsen, tel.: +45 7488 4438, fax: +45 7488 3358 or e-mail: [email protected]

Characteristic Compact design Open terminals Universal screws Screwdriver guide DIN rail holder Status indication Short-circuit protection Phase failure protection

Advantage No gap between units Fast wiring One screwdriver Pozidrive 2/Slot 3 Fast wiring Vertical or horizontal mounting Rapid overview Cuts out all three phases Fast cut-out on 2-phase operation

Benefit Saves space Saves time Saves time Saves time Saves space Saves repair time Gives extra safety Saves money

0.1 0.16 0.25 s s

0.4 0.63 s s

1.0 s

1.6 s

2.5 s s s s s

4.0 s s

6.3 s s

Short-circuit and overload protection of motors s s s s s s Short-circuit protection of electrical plant s s s s s

10 s s s s s

16 s s s s s s

20 s s s

25 s s s s s





s s

s s




s s s

Short-circuit and overload protection of transformers Complete overview at a glance

[A] Basic type 1 CTI 25 M Basic type 1 CTI 25 MB Basic type 1 CTI 45 MB Basic type 2 CTI 25 S Basic type 2 CTI 25 SB Basic type 3 CTI 45 SB Basic type 3 CTI 16 T Basic type 3 CTI 20 TB Basic type 3 CTI 32 TB

CTI 25M, S and CTI 16T high break capacity CTI 25/45 MB, SB and CTI 20/32 TB extra-high break capacity



MCD 3000 Soft Starter

The Danfoss product range comprises refrigeration and air conditioning controls, components for burners and boilers, comfort controls, industrial controls, water hydraulics, compressors for refrigerators and freezers, thermostats for refrigerators and freezers, heating and ventilating controls, electrical drives and controls, instrumentation, compressors for commercial refrigeration and water valves.




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