Siemens MCC-3298 user manual Error Condition

4 Troubleshooting

Error Condition

Incomplete

Sequence

External Trip

CPU Fault

Troubleshooting Guide

Main Cause		Remedy
Indicates the SAMMS-LV unit does not	1. If the unit trips one second after start, verify that
detect current one second after a start		current transformer secondary input is present in the
command, or it detects current one		range of 100 mVAC to 3.54 VAC at terminals 1, 2,
second after a stop command.		and 3 with reference to 4. Verify that the coil voltage
		is 115 VAC at terminals 14, 15, or 16 with reference
		to 13 when the motor is started. Verify 115 VAC at
		terminal 7 with reference to 13. Correct conditions if
		necessary. Call Siemens if unit continues to trip.
	2. If the unit trips one second after a stop command,
		verify the contactor is open. Repair or replace the
		contactor if it is not functioning properly.
	3. Verify operation of mechanical interlock, and replace
		or adjust.
	4. Verify absence of voltage at terminals 1, 2, and 3 with
		reference to 4, and at terminals 14, 15, or 16 with
		reference to 13. If voltage is present, define the
		source and reconnect so that the motor current only
		passes through the current transformer.
	5. To disable incomplete sequence, select F1 on the
		HHC, press the ENTER key for one or more seconds
		and start the motor. The incomplete sequence will
		remain disabled until the above procedure is
		repeated.
If the external trip LED is solidly	1. Jam conditions such as a blocked conveyor belt or
illuminated and the motor is stopped, it		gear train cause a sudden increase in motor current,
indicates a jam or loss of load		which can damage the motor’s insulation in a short
condition.		period of time.
	2. Loss of load conditions, such as a broken blade of an
		impeller or loss of back pressure of a pump, result in
		a sudden decrease in motor current.
	3. F16 on the HHC displays the external trip current at
		the time of the trip.
		In any case, determine the reason for the external trip
		and correct the problem before restarting the motor.
		If the external trip LED flashes and the motor
		continues to run, it indicates loss of load warning or
		process current warning.
Indicates a problem in the		Verify voltage between terminals 5 and 6 is more than
microprocessor or a low voltage		10 VAC. If fault persists, call Siemens.
condition.

40