Circuit Breaker - Troubleshooting Guide

Symptoms Table

Symptom	Probable Cause	Solution
Alarm 552 TRIPPED CIRCUIT BREAKER	There is a short circuit on the Coolant Pump Motor or Cable.	Refer to the Standard Coolant - Troubleshooting Guide : Defective Pump section.
	The circuit breaker is defective.	Test the circuit breaker inrush current and duration time. Refer to the Coolant Pump Breaker Troubleshooting section below.
	The PSUP PCB is defective.	If the machine generates alarm 552 and the circuit breaker did not trip, then the PSUP may be at fault. Refer to the PSUP PCB Troubleshooting Guide: PCB Inspection component section.

Coolant Pump Circuit Breaker

This guide is meant to be used for troubleshooting circuit breakers 61-7361 (10A) and 61-7352 (15A) used for machine coolant applications.
Note: This guide does not apply to the Variable Flow coolant or the Shower coolant option as these use VFDs.

Required Tools:

AC Clamp Meter able to measure Inrush Current

The table below shows the coolant pump and circuit breaker combination used for the various coolant options.

Coolant Options	Coolant Pump Motor	Circuit Breaker
Coolant Options	Motor Rating / Phases	Current Rating	Location
Standard flood coolant	1.00HP / 3PH or 0.25HP / 1PH	10A	PSUP PCB
High pressure flood coolant	1.50HP / 3PH	10A	PSUP PCB
TSC 300 PSI	1.50HP / 3PH	15A	PSUP PCB or TMD PCB
TSC 1000 PSI	3.00HP / 3PH	15A	PSUP PCB or TMD PCB

Measure the Inrush Current and Duration Time

Figure 1: I/O PCB motor power cable connections. Figure 2: TMD PCB motor power cable connection.

1

Trace back the pump power cable to locate the connection point inside the electrical control.

This will either be on the I/O PCB P29, P31 or the TMD PCB P1 which is mounted on the I/O hinge door depending on the machine.

NOTE FOR TSC

If the strip length on the TSC pump power cable is too tight to fit a current clamp around the individual conductors, the inrush and nominal running current can be measured from cable 33-1980 connected to I/O PCB P30.

If the pump power cable is connected to the I/O PCB. On cable 33-1980 the gray conductor is phase A (77), the orange is phase B (78), and the brown is phase C (79).

If the TSC pump power cable is connected to the TMD PCB, then the inrush and nominal running current can be measured from cable 33-0987B connected to P4 on the TMD PCB.

On cable 33-0987B the red conductor is phase A (77), white is phase B (78), and black is phase C (79).

Figure 3: Correct method to measure current. Figure 4: Incorrect method to measure current.

2

Using a current clamp meter set to measure the Max/Inrush AC current, clamp the meter around a single conductor on the cable.

Turn the pump on and measure the inrush current and its duration time which is the time from the moment the pump is turned on to the time the circuit breaker trips.

Repeat this 2-3 times making sure to record the inrush current and duration time. Repeat this step on all the remaining conductors on the power cable excluding the green ground conductor.

3

Compare the recorded inrush currents and duration times to the NOMINAL COOLANT PUMP INRUSH CURRENT VALUES PER PHASE table on Figure 6.

If the breaker did not trip, measure the nominal running current of the pump as described in the section below.

Figure 6: Known nominal inrush values per motor phase for coolant pumps. Values are nominal +/- 20% of the value listed.

NOTE: For TSC and High Pressure Coolant options, do not measure the inrush current with the pump out of the coolant reservoir as these have a pressure switch which will alarm out.

Nominal Coolant Pump Inrush Current Values per Phase
Pump Motor	Red Conductor	White Conductor	Black Conductor
Pump Motor	Phase A (77)	Phase B (78)	Phase C (79)
Rating / Phases	Inside Coolant Reservoir	Inside Coolant Reservoir	Inside Coolant Reservoir
0.25HP / 1 PH (SINGLE PHASE MOTOR)	-	5 A	5 A
1.00HP / 3PH	17 A	17 A	17 A
1.50HP / 3PH (TSC)	25 A	25 A	25 A
3.00HP / 3PH (TSC)	32 A	32 A	32 A

Measure the Nominal Running Current

To measure the nominal running current of the pump, the coolant hose at the machine needs to be disconnected to prevent head pressure from skewing the nominal running current measurement.

IMPORTANT: This does not apply to TSC and the High Pressure Coolant option.

Figure 7: Pump hose for Flood Coolant.

1

Disconnect the coolant hose [7] from the machine and secure the hose tightly to the coolant tank reservoir. This is important as not securing the hose will cause it to spray coolant everywhere.

Figure 8: Correct method to measure current. Figure 9: Incorrect method to measure current.

2

Using a current clamp meter set to measure nominal AC current, clamp the meter around a single conductor on the power cable. After checking the pump hose is secured, turn the pump on and let it run for 5 seconds.

Record the nominal running current from the current clamp and then stop the pump. Repeat this step for all the remaining conductors on the power cable making sure to record the nominal running current for each conductor excluding the green ground conductor.

3

Remove the pump from the coolant reservoir and repeat step 2 and 3 with the coolant pump outside of the coolant reservoir.

4

Compare the recorded nominal running current values from step 2 and 3 to the known nominal running current values for the specific pump size as shown below.

If the recorded nominal current values are within the known nominal current values +/- 20%, then the pump and circuit breaker are not faulty and the other parts of the coolant system should be inspected.
If the recorded nominal current values are higher than the known nominal running current values shown, then the pump needs to be inspected for any faults which could be causing the higher running currents.

Figure 10: Known nominal running current values per motor phase for coolant pumps. Values are nominal +/- 20% of the value listed. For TSC and High Pressure Coolant options, do not measure the nominal running current with the pump out of the coolant reservoir as these have a pressure switch which will alarm out.

Known Nominal Coolant Pump Running Current Values per Phase
Pump Motor	Red Conductor		White Conductor		Black Conductor
Pump Motor	Phase A (77)		Phase B (78)		Phase C (79)
Rating / Phases	Inside Coolant Reservoir	Outside Coolant Reservoir	Inside Coolant Reservoir	Outside Coolant Reservoir	Inside Coolant Reservoir	Outside Coolant Reservoir
0.25HP / 1 PH	-	-	1.3 A	0.6 A	1.3 A	0.6 A
1.00HP / 3PH	3 A	1.2 A	3 A	1.2 A	3 A	1.2 A
1.50HP / 3PH (TSC)	3.0 A	Do not measure	3.0 A	Do not measure	3.0 A	Do not measure
3.00HP / 3PH (TSC)	4.5 A	Do not measure	4.5 A	Do not measure	4.5 A	Do not measure