15
19. Checking motor and cable
20. 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.
1.
Supply voltage
TM
0
0
1
371
3
5
97
Measure the voltage between the phases with
a voltmeter.
Connect the voltmeter to the terminals in the
motor starter.
The voltage should,
when the motor is loaded
, be
within ± 5 % of the rated voltage. The motor may burn
if there are larger variations in voltage.
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 the supply voltage indicate poor
electricity supply, and the pump should be stopped
until the defect has been found.
Resetting of the motor starter may be necessary.
2.
Current consumption
TM
00 137
2 359
7
Measure the current of each phase while the
pump is operating at a constant discharge
pressure (if possible at the capacity where the
motor is most heavily loaded).
For normal operating current, see the
“Technical specification”.
The difference between the current of the phase with
the highest amp consumption and the one with the
lowest amp consumption must not exceed 10 % of the
lowest amp consumption.
If so, or if the current exceeds the rated current, check
these possible faults:
• A damaged pump is causing the motor to be
overloaded. Pull the pump out of the sleeve for
overhaul.
• The motor windings are short-circuited or partly
disjointed.
• Too high or too low supply voltage.
• Poor connection in leads. Weak cables.
Points 3 and 4: Measurement not needed if supply voltage and current consumption are normal.
3.
Winding resistance
TM
00
13
73
35
97
Remove the phase leads from the terminal
box.
Measure the winding resistance as shown on
the drawing.
The highest value must not exceed the lowest value by
more than 5 %.
If the deviation is higher, and the supply cable is OK,
the motor should be overhauled.
4.
Insulation resistance
TM
00
13
74
35
97
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.)
The insulation resistance for a new, cleaned or
repaired motor must be approx. 10 M
Ω
measured to
earth.
For a given motor the critical insulation resistance
(R
crit
) can be calculated as follows:
R
crit
= U
N
[kV] x 0.5 [M
Ω
/kV].
If the measured insulation resistance is lower than
R
crit
, the motor must be overhauled.
Subject to alterations.
