Baker D30R User Manual - page 52

Surge Test Applications 

12/3/2009 | 71-022 V6 

D30R 

52 

32)

For capacitor-started motors or systems with surge arrestors/power factor 

capacitors, be sure to 

disconnect

 all capacitors from the test circuit 

before 

testing. 

33)

Upon completion of a DC High Potential, Megohm, Polarization Index, Step Voltage, 

Dielectric absorption, or Continuous Ramp test, before disconnecting the test leads, 

short the winding, motor, etc., to ground and allow time for discharge. If this is not 

done, voltage may still be active on leads and tested components. 

34)

Make sure

 the tester leads are disconnected before the motor is energized or 

powered up. 

35)

Do not

 remove the product covers or panels or operate the tester without the 

covers and panels properly installed. Components on inside of tester carry voltage 

for operation and if touched can render a shock. 

36)

Use appropriate safety equipment required by your organization, including high 

voltage globes and eye protection. 

37)

Repair Parts Warning

: Defective, damaged, or broken test leads must be replaced 

with factory-authorized parts to ensure safe operation and maintain performance 

specifications. 

38)

Ground the product: 

This product is grounded through the grounding conductor of 

the power cord. To avoid electrical shock, plug the power cord into a properly 

wired/grounded receptacle before connecting the product test leads. 

Danger from loss of ground – Upon loss of the protective ground connection, 

all accessible conductive parts, including knobs and controls that may appear 

to be insulated, can cause an electric shock! 

39)

This instrument is 

NOT

 waterproof or sealed against water entry. 

40)

The unit is for indoor use. If used outdoors, the unit must be protected from rain, 

snow and other contaminants. 

Maintenance testing 

The following are guidelines for performing surge tests on a variety of assembled motors, 

coils, transformers, rotors, etc in the field or shop as part of maintenance and quality testing. 

Hard-shorted winding faults are rarely found in motors during maintenance testing. Solid 

turn-to-turn winding faults happen when the insulation on adjacent copper wires has failed to 

the point that the adjacent wires are welded together. It is a rare for periodic maintenance 

testing because of a transformer action which occurs within the windings which induces very 

high current in a hard turn-to-turn short. The high current causes heating and deterioration 

of the surrounding insulation systems. The single turn-to-turn short rapidly compounds until 

the damage causes a failure in the ground wall insulation. The high current will trip the circuit 

breaker and stop the motor. This condition is usually only found after the motor has failed.  

The key to the surge test for maintenance is to detect a fault at a voltage level above the peak 

operating voltage but not above what the motor would general see during start-up. For 

example, a 13200 V motor that shows a good trace at 14250 V but shows an unstable, 

flickering patter, (regardless of rotor coupling) at 24000 V definitely contains a fault. When 

the fault is detected above operating voltage, time is available to schedule service for the 

motor before a hard short and rapid failure occurs. 

During surge testing, steady separation in the wave pattern comparisons is most often the 

result of the rotor coupling with the stator. (See Rotor Loading (Coupling) when testing