Checking Of Motor And Cable; Disposal - Grundfos BM Series Installation And Operating Instructions Manual

15. Checking of motor and cable

1. Supply voltage
Voltmeter
2. Current consumption
Ammeter
Items 3 and 4: Measurement not necessary if supply voltage and current consumption are normal.
3. Winding resistance
Ohmmeter
4. Insulation resistance
Megohmmeter

16. Disposal

This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
2. If this is not possible, contact the nearest Grundfos company
or service workshop.
Measure the voltage between the
phases by means of a voltmeter.
Connect the voltmeter to the terminals
in the motor-protective circuit breaker.
Measure the current of each phase
while the module is operating at a
constant discharge pressure (if
possible at the capacity where the
motor is most heavily loaded).
For normal operating current, see
nameplate.
Remove the phase leads from the
terminal box.
Measure the winding resistance as
shown on the drawing.
Remove the phase leads from the
terminal box.
Measure the insulation resistance from
each phase to earth (frame).
Make sure that the earth connection is
made carefully.
Subject to alterations.
The voltage should, when the motor is loaded, be within - 10
%/+ 6 % of the rated voltage. In case of larger variations in
voltage, the motor may burn.
If the voltage is constantly too high or too low, the motor must
be replaced by one corresponding to the supply voltage. Large
variations in voltage indicate poor power supply, and the
module should be stopped until the fault has been found.
Resetting of the motor-protective circuit breaker may be
necessary.
Calculate the current unbalance (%) in the three phases as
follows:
1. Add up the three phase currents.
2. Divide this value by three to ascertain the average current.
3. Find the phase current differing most from the average
current.
4. Compare the results from points 2 and 3.
5. Divide the difference by the average value and multiply by
100. The result is the current unbalance in %.
For three-phase motors, the current unbalance must not
exceed 5 %. If so, or if the current exceeds the maximum
operating current, there are the following possible faults:
• The contacts of the motor-protective circuit breaker are
burnt. Replace the contacts.
• Poor connection in leads, possibly in terminal box.
• Too high or too low supply voltage. See point 1.
• The motor windings are short-circuited or partly disjointed.
See point 3.
• Damaged pump is causing the motor to be overloaded. Pull
the pump out of the sleeve for overhaul.
• The resistance value of the motor windings deviates too
much. Move the phases in phase order to a more uniform
load. If this does not help, see point 3.
The highest value must not exceed the lowest value by more
than 10 %. If the deviation is higher, pull the pump out of the
sleeve. Measure motor and cable separately, and replace or
repair defective parts. See section
If the measured insulation resistance is less than 0.5 MΩ and
the supply cable is OK, pull the pump out of the sleeve for
motor or cable repair or replacement. See section
documentation.
14. Service documentation.
14. Service
9