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GUIDE TO USING CELEM CAPACITORS

1. Choosing the Best Capacitor for Your Needs

When choosing a capacitor for an application, select a capacitor with maximum rated voltage RMS, current and reactive power that most closely matches the highest operating voltage and frequency of the application. The maximum ratings appear clearly on the data sheet of each capacitor.

The reactive power formula is:

Qc= V2rms x C x 2πf x 10-6

where 

Qc is reactive power in kVAr

Vrms is RMS voltage in volts

C is capacitance in µF

f is frequency in kHz

2. Proper Cooling and Termination for Power Capacitors

Celem water-cooled capacitors are constructed to ensure that all elements are cooled uniformly and handle power equally.

Celem conduction-cooled power capacitors handle a large amount of power in relatively small volume. In order to operate correctly, capacitors must be terminated properly to ensure uniform cooling of all internal elements.

Four critical requirements must be addressed when using conduction-cooled capacitors:

1. Cooling. The entire area of the capacitor’s contacts surface must be placed in contact with the heat sink using a thermal conductive paste to ensure optimal heat conductance. This is particularly critical when the capacitor is working at its maximum limits.

2. Conduction losses. Most power capacitors are able to supply hundreds of amperes. When several capacitors are connected to a common collector, insufficient collectors’ surface area may result, due to the skin effect, in extreme heating of the bus bar where the current is collected, despite proper cooling.

3. Induction heating of capacitors. When several conduction-cooled capacitors are assembled between two bus bars, those located closest to the output terminals may experience induction heating. This situation should be avoided by mounting the capacitors as illustrated in diagram B or by building a low inductance path between the bus bars as illustrated in diagram C.

4. Stray inductance. Even when a capacitor bank is not connected directly to a work coil, it is good practice to avoid stray inductance in the circuit. Inductance is proportional to the bus bars’ lengths, inversely proportional to their widths and inversely proportional to the distance between the bus bars.

3. Capacitor Bank Losses

A capacitor bank consists of capacitors and connections between the capacitors and output terminals. Losses may be associated with either of these elements.

Capacitor losses. Losses in the capacitors are extremely low, generally about 5 x 10-4 x the reactive power.

Connection losses. In a properly constructed capacitor bank, connection losses will be approximately the same as the capacitor losses.

Total capacitor bank loss is equivalent to the sum of the capacitor losses and connection losses. As such, it generally totals about 10-3 of the reactive power.

4. Required Water Flow for Capacitor Bank Cooling

Most capacitors available today, which use polypropylene as a dielectric, can safely run at temperatures of up to 90°C. The temperature gradient between the hottest points of the polypropylene element and the copper surface of Celem capacitors is 40-45°C. Therefore, external surfaces of the capacitors must not exceed 45°C. In practice, the cooling water temperature at the outlet of the cooling circuit should not exceed 40°C.

When the capacitor bank is cooled in series with the work coil, the losses of the work coil are at least ten times that of the capacitor bank. Therefore, the capacitor bank should be cooled first, followed by the work coil.

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Num of Ratings: 3  Average: 5
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Information

Celem Passive components Ltd.

Celem Passive Components Ltd.

12/2 Hi Tech village, Givat Ram

P.O. Box 39109

Jerusalem 91390, ISRAEL

Tel.  +972 2 6788305

Fax. +972 2 6536094

Tel.  + 972 2 6788305

Fax. + 972 2 6536094

Email: Celem Techsupport

Sun-Fly Shenzhen

 

www.sun-fly.com.cn

Tel .  +86 755-86219349

Fax. 0755-86219305

Mobile : 13502898396

Shenzhen Yesia

Tel.  +86 755-8375 4665

Fax. 0755-83754673

Beijing Wellfront Electronic Co.,

www.wellfront.com

Tel.  +86 10 51266538

Fax. +86 10 51266538

SunFly (HK) Electronics Technology

www.sun-fly.com.cn

  Tel.  +852-29712883

Fax. +852-30137680

India

SCM Future Technologies

  Tel +91-98732-22934

Tel. +91-98103-27979
Telefax+91 120 4991807

ELCA ACS Srl

www.elcaacs.it

Tel.  +39 02 66301574

Fax. +39 02 66301576

J REP Corporation - Tokyo

www.j-rep.com

Tel.  +81-3-5789-2310

Fax. +81-3-3449-7844

J REP Corporation - Osaka

www.j-rep.com

Tel.  +81-6-6368-2111

Fax. +81-6-6368-2114

DACPOL Co. Ltd.

www.dacpol.com.pl

Tel.  +48 22 7035100

Fax. +48 22 7035101

New Technologies Ltd. 

           169, Nemirovich-Danchenko str.
Novosibirsk, 630073, 

   RUSSIAN FEDERATION

Tel.  +7 383 315 3177

http://ntcom.ru

AGF Technology

www.agftechnology.com

Tel.  + 27 (0) 11 623 1943

Fax. + 27 (0) 11 623 1951

Kyungdo Industrial Co

Tel.  +82 2 954 0713

Fax. +82 2 954 1477

Euro Entech Co.

Tel.  +82-31-479-7680

Fax. +82-31-479-7681

Daan Electronics co. DAEGU. 

 Tel. +82 53 6042651

Fax. +82 53 6042650

Jackson Transformer co.

6800 Benjamin road

Tempa,   FL 33634

Jackson Transformer

Tel.    +1 813 879 5811

Fax:    +1 813 870 6405

North & South America 
Richardson Electronics www.rell.com
Tel.1-800-348-5580 
Tel. 1-630-208-2200

Eurocomp Elektronik GmbH

www.eurocomp.de

Tel.  +49 6032 9308 33

Fax. +49 6032 9308 30

Jilin Coway M&E Eqmts Co.,Ltd.
Tel.  +86 431-87949733

    Fax. +86 431-87949133 
Mobile.  15044155788