Preliminary Checks; Current Measurement - Grundfos UP 200 Serie Instrucciones De Instalacion Y Operacion

6.2 Preliminary checks

Supply voltage
To check the voltage being supplied to the
motor, use a voltmeter.
WARNING
Be careful, since power is still being
supplied to the pump. Do not touch
the voltmeter leads together while
they are in contact with the power
lines.
Single-phase motors
Touch one voltmeter lead to each of the lines
supplying power to the pump, L and N.
Fig. 10 Checking single-phase power
Evaluation
When the motor is under load, the voltage
should be within 10 % (+ or -) of the nameplate
voltage. Any variation larger than this may
indicate a poor power supply and can cause
damage to the motor windings. The motor
should not be operated under these conditions.
Contact your power supplier to correct the
problem or change the motor to one requiring
the voltage you are receiving.

6.3 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
information on the nameplate.
Evaluation
If the current exceeds the listed nameplate
amps, 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
winding 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. 11 Current measurement
11