Flowserve Byron Jackson Type M - Manual (Page 53)

® Byron Jackson Double Mechanical Seal Submersible Pumping Unit • 1042.293/9 • June 04
Page 53 of 68
•
Shut-off head reduced by 10 % - 15 %
Undertake maintenance before the next check
period.
•
Shut-off head reduced by > 15 %
The pump requires immediate attention and
should not be run further.
6.8 Electrical tests of the motor
DANGER
Do not conduct this test in an area
that has been designated a hazard-
ous location.
6.8.1 Insulation test
Before initial starting, as well as after longer stor-
age or idle time, the insulation resistance of the
drive must be measured.
DANGER
During and after the measurement,
the connector ends of the motor line
and/or the connection terminals
partly carry dangerous voltage and
may not be touched.
Before the measurement, ensure
that there is no line voltage.
To measure the insulation, disconnect all leads of
the power cable of the motor.
All leads must carefully be cleaned of all dirt. Heed
the operating instructions of the insulation measur-
ing device.
Insulation measurement is always performed with
a measuring-circuit voltage of 1000 V. The meas-
ured value must be read after a minute of meas-
urement duration.
DANGER
The motor windings or power cable,
charged up to the measuring-circuit
voltage, must be discharged after
measurement by means of the insu-
lation measuring device.
The limits for minimum insulation resistance and
critical insulation resistance for measurements at
20 °C winding temperature are as follows:
•
Critical insulation value after
longer operational time ..........................10 M
Ω
CAUTION A relatively low insulation resis-
tance does not definitely show that
the pumping unit will break down
due to insulation problems.
If however after measurements over
a longer period of time, an extreme
drop in the insulation resistance
occurs within a short time, these
must then be inspected.
If the insulation resistance falls below minimum
value, the cause or the malfunctioning part (power
cable, line connection or windings) must be deter-
mined and the insulation weakness removed.
6.8.2 Continuity testing
1. For continuity testing of the motor stator wind-
ings, use low resistance Ohm-Meter (4-pole
Kelvin Bridge)
2. Perform continuity test with motor. The termi-
nal resistance must first be measured in the
three possible combinations (1-2, 1-3, 2-3).
These three values must not vary by more
than ± 2% from their average. The terminals
must be grounded before the low resistance
Ohm-Meter leads are connected. The tem-
perature of the winding in °C must also be
measured and recorded.