TP-6953 7/19124 Section 7 Troubleshooting
7.6.2 Faults Shown
Step Potential Cause
Explanation Troubleshooting
Fault: System Voltage Mismatch Between Generators
1 System voltage is not
equivalent
One of the controllers on the network is configured differently than the other
controllers. This will inhibit any of the generators from closing to the bus.
Verify the system voltage of all the generators match the requirements of
the site.
Fault: System Frequency Mismatch Between Generators
1 System frequency is
not equivalent
One of the controllers on the network is configured differently than the other
controllers. This will inhibit any of the generators from closing to the bus.
Verify the system frequency of all the generators match the requirements of
the site.
Fault: Phase Connection Mismatch Between Generators
1 Phase connection is
not equivalent
One of the controllers on the network is configured differently than the other
controllers. This will inhibit any of the generators from closing to the bus.
Verify the phase connection of all the generators match the requirements of
the site
.
Fault: Live Bus Sensed When Dead Bus Expected
1 Bus is considered to
be live
The controller is measuring voltage on the paralleling bus. This will inhibit the
breaker from closing.
Check bus for residual voltage (sometimes induced by large transformers or
motors). Possibly, adjust the Dead Bus Threshold to accommodate the
residual voltage.
2 Bus sensing is not
connected
The controller may see voltage on the paralleling bus when the generator is
operating and the bus sensing is disconnected.
Verify the bus sensing wiring is connected to the load side of the
motor-operated breaker for this generator.
Fault: Close Attempt
Fault: Fail to Close
1 Breaker is unable to
close
The controller is attempting to close the circuit breaker but the breaker is not
closing.
Watch the ready flag on the motor operator of the circuit breaker, if
equipped. If it indicates not ready when the engine is stopped and toggles
to the ready state when the generator is trying to close the breaker, the trip
coil is acting correctly. Continue at Step 5 otherwise, continue on to Step 2.
2 Trip is not removed
from the circuit breaker
The controller is attempting to close the circuit breaker but the breaker is not
closing because the trip coil is still energized.
If the ready flag of the motor operator indicates ready when the engine is
stopped, continue at Step 3 otherwise, continue on to Step 4.
3 CB trip relay is wired
as normally open
The controller is expecting that the trip on the circuit breaker is a
normally-closed contact. This is intentional as it holds a trip on the breaker if
the controller is removed.
Verify the CB trip relay is wired to hold a trip on the breaker when the relay
is not energized.
4 Incorrect wiring
between the CB trip
relay and the trip coil
on the breaker
The CB trip relay is operating correctly but the trip coil on the breaker is
remaining energized. This could be due to incorrect wiring between the
generator controller and the circuit breaker.
Verify the wiring to the circuit breaker.
5 Close is not applied to
the circuit breaker
The breaker trip is removed but the controller is not able to close the breaker. Verify the wiring between the generator controller and the circuit breaker
close coil. Check the close coil to ensure that it is not defective.
6 Breaker is not charged The breaker is receiving the signal to close but the energizing spring is not
charged.
Verify the motor operator is receiving voltage at the appropriate contacts to
allow it to wind the spring.
7 Breaker is not powered The 24V electronics on the circuit breaker require an external 24V source on a
12V generator.
Verify the 24V input which exists on paralleling generators is receiving
24VDC in the correct polarity.
8 Wiring to power is not
complete
There is no voltage to the CB close relay on this circuit breaker. Connect the supply to the CB close relay to either 24V from wire #70 or an
external 24VDC supply (with battery storage).
9 Breaker status
feedback is not valid,
no bus sensing
The breaker closes but the controller does not see a change in status. The
controller cannot see the bus is energized as the bus sensing is not connected
correctly on any generators on the network.
Verify the wiring on the circuit breaker to ensure that it is connected
correctly. Verify bus wiring for all nodes. Verify the generator output is
connected to the line side of the generator breaker.
10 Standalone mode
enabled (with no circuit
breaker equipped)
The generator set expects to have a circuit breaker, even without PGEN
communications, if the standalone mode is enabled.
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