DSH 440 Short-circuit of motor capacitors
http://decisions.iecee.org/icons/ecblank.gif DSH 440
Short-circuit of motor capacitors
19.7
60335-1(ed.3)
Standard: IEC60335-1:1991, 3rd Ed.
Sub-clause: 19.7
Sheet No. DSH-440
Subject: Short-circuit of motor capacitors
Key words: -short circuit -motor capacitor
Decision taken at the 40th CTL meeting 2003.
Question:
TC 61 requested CTL to clarify the test procedure for short-circuiting capacitors in accordance with Sub
clause 19.7 of IEC 60335-1.
Decision:
If the design of the circuit is such that short-circuiting of one capacitor will result in the short-circuiting
of the second capacitor, only one capacitor needs to be short-circuited. This is endorsed by the sub clause
4.3 that states “If it is evident from the construction of the appliance that a particular test is not
applicable, the test is not made”.
The followings are examples of the circuits.
In the Example A:
Short-circuit of capacitor (Cb) terminals is necessary according to the requirements. For the
capacitor (Ca), short-circuit of its terminals when motor is running is not necessary because
the circuit is opened (the switch is opened).
Also short circuit of its terminals (Ca) when the motor starts is not necessary because it is
already covered by the short-circuit of Cb terminals.
In the Example B:
Only one short-circuit, either Cb1 or Cb2 terminals, is necessary because the testing of one
covers the testing of the other one. Also the short-circuit of Ca terminals is not necessary
because of the reason stated in the Example A.
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