Checking Motor And Cable; Disposing Of Hazardous Or Toxic Materials - Grundfos SP Series Installation And Operating Instructions Manual

11. Checking motor and cable

DANGER
Electric shock
Death or serious personal injury
- Switch off the power supply before you start any
work on the product.
- Make sure that the power supply cannot be
accidentally switched on.
1. Supply voltage
Measure the voltage between the phases
by means of a voltmeter.
On single-phase motors, measure
between phase and neutral or between
two phases, depending on the type of
supply. Connect the voltmeter to the
terminals in the motor-protective circuit
breaker.
2. Current
consumption
Measure the amps of each phase while
the pump is operating at a constant outlet
head (if possible, at the performance
where the motor is most heavily loaded).
For maximum operating current, see
nameplate.
Items 3 and 4: Measurement is not necessary when the supply voltage and the current consumption are normal.
3. Winding resistance
Disconnect the submersible drop cable
from the motor-protective circuit breaker.
Measure the winding resistance between
the
4. Insulation
resistance
Disconnect the submersible drop cable
from the motor-protective circuit breaker.
Measure the insulation resistance from
each phase to earth (frame). Make sure
that the earth connection was made
carefully.
12.

Disposing of hazardous or toxic materials

DANGER
Toxic or radio active liquid
Death or serious personal injury
- If a pump has been used for a liquid which is
injurious to health or toxic, the pump will be
classified as contaminated.
leads conductors of the drop cable.
The voltage must, when the motor is loaded, be within the
range specified in section 6. Electrical
The motor may burn if there are larger variations in voltage.
Large variations in voltage indicate poor power supply, and
the pump must be stopped until the defect has been
remedied.
On three-phase motors, the difference between the current in
the phase with the highest consumption and the current in the
phase with the lowest consumption must not exceed 5 %. If
so, or if the current exceeds the rated current, there are the
following possible faults:
• The contacts of the motor-protective circuit breaker are
burnt.
Replace the contacts or the control box for single-phase
operation.
• Poor connection in leads conductors, possibly in the cable
joint.
See item 3.
• Too high or too low supply voltage. See item 1.
• The motor windings are short-circuited or partly disjointed.
See item 3.
• Damaged pump is causing the motor to be overloaded.
Pull out the pump for overhaul.
• The resistance value of the motor windings deviates too
much (three-phase). Move the phases in phase order to a
more uniform load. If this does not help, see item 3.
For three-phase motors, the deviation between the highest
and the lowest value must not exceed 10 %. If the deviation is
higher, pull out the pump. Measure motor, motor cable and
drop cable separately, and repair or replace defective parts.
Note: The operating winding of single-phase 3-wire motors
will assume the lowest resistance value.
If the insulation resistance is less than 0.5 MΩ, the pump must
be pulled out for motor or cable repair.
Local regulations may specify other values for the insulation
resistance.
connection.
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