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8. TROUBLE-SHOOTING
Should the relay appear defective, proceed as follows:
- Check that the thumbwheel switch of the neutral current element in the KZ91 or
KZ91-1 is not set to zero.
- Check the + 15 V and + 24 V auxiliary supplies are in order at the edge
connector of each plug-in unit (see relative instructions for the terminal
designations of the DC/DC converter) •
- Check the correctness of the signals at the sockets on the front of the EW91
(see Section 6.3). If not, check the relay wiring.
- Localise a defect
by
withdrawing the KI or KZ unit and rechecking the signals
at the sockets on the EW91. If they are in order, a defective main processing
unit is to be suspected.
- Replace the defective unit.
Should it not be possible to locate and clear a defect, then the complete relay
or plug-in unit concerned must be returned to the nearest BBC agent, or directly
to ABB Baden, Switzer land.
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