Siemens vacuum circuit breaker 38-3AH3 38 kV - Manual (Page 61)

Maintenance and
troubleshooting
Problem Symptoms Possible causes and remedies
Nuisance or false close Electrical problem 1. Nuisance or false closing signal to secondary
disconnect 13. Check protective relay logic.
Correct as required.
2. Closing coil (52SRC) terminal A2 is shorted-
to-ground. Check to determine if problems
are in wiring or coil. Correct as required.
Mechanical problem 1. Mechanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field service
at +1 (800) 347-6659 or +1 (919) 365-2200
outside the U.S.
Circuit breaker will not trip Tripping coil or solenoid (52T) does not
energize. There is no tripping sound. 1. Secondary control power is de-energized or
control power fuses are blown. Correct as
indicated.
2. Damage to wiring, terminals or connectors.
Check and repair as necessary.
3. No tripping signal to secondary disconnect
contact 1. Check for continuity and correct
protective relay logic.
4. Secondary disconnect contacts 1 or 2 are not
engaging. Check and replace if required.
5. Failure of trip coil (52T). Check and replace if
necessary.
6. Auxiliary switch NO contacts 23 to 24 or 33
to 34 are OPEN when circuit breaker is
CLOSED. Check linkage and switch. Replace
or adjust as necessary.
Tripping coil (52T) energizes. No tripping
sound is heard, and circuit breaker contacts
do not open. In other words, they remain
CLOSED. 1. Failure of tripping spring or its mechanical
linkage. Check and replace if required.
Tripping coil (52T) energizes. Tripping sound
is heard, but circuit breaker contacts do not
open. 1. Mechanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field service
at +1 (800) 347-6659 or +1 (919) 365-2200
outside the U.S.
2. One or more of the vacuum interrupters are
held CLOSED. Check and replace as
necessary.
Nuisance or false trip Electrical problem 1. Tripping signal remains energized on
secondary-disconnect contact.
2. Check for improper protective relay logic.
Mechanical problem 1. Mechanical failure of operating mechanism.
Check and contact regional service centers,
the factory or telephone Siemens field service
at +1 (800) 347-6659 or +1 (919) 365-2200
outside the U.S.
Table 7: Troubleshooting (continued)
61