Grundfos VersaFlo UPS, Installation And Operating Instructions Manual

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5.3 Current measurement
To check the current, use an ammeter.
To do so, follow these steps:
1. Make sure the pump is operating.
2. Set the ammeter to the proper scale.
3. Place the tongs of the ammeter around the leg to
be measured.
4. Compare the results with the amp draw informa-
tion on the motor nameplate.
5. Repeat for the other legs.
Evaluation
If the current draw exceeds the listed nameplate
amps, or if the current imbalance is greater than 5%
between each leg on three-phase units, then check
the following:
• The voltage supplied to the pump may be too high
or too low.
• The contacts on the motor starter may be burned.
• The terminals in the starter or terminal box may be
loose.
• There may be a winding defect. Check the wind-
ing and insulation resistance.
• The motor windings may be shorted or grounded.
• The pump may be damaged in some way and may
be causing a motor overload.
• A voltage supply or balance problem may exist.
Fig. 19 Current measurement
5.4 Insulation resistance (lead-to-ground)
To check the insulation resistance (lead-to-ground)
of the motor and leads, a megohmmeter is required.
To do so, follow these steps:
1. Turn the POWER OFF.
2. Disconnect all electrical leads to the motor.
3. Set the scale selector on the megohmmeter to
R x 100K, touch its leads together, and adjust the
indicator to zero.
4. Touch the leads of the megohmmeter individually
to each of the motor leads and to ground
(i.e. L1 to ground; L2 to ground, etc.).
Fig. 20 Insulation resistance measurement
Evaluation
The resistance values for new motors must exceed
1,000,000 ohms. If they do not, replace the motor.
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M
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