Nord Drivesystems B1091, Operating Manual With Installation Instructions

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1 General
B 1091 en-1221 17
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1.3.8 Checking the insulation resistance
Prior to initial commissioning of the motor after a long period of storage or standstill (approx. 6
months) the insulation resistance of the windings must be checked. During and immediately after the
measurements, the terminals have voltages which can be dangerous, and must not be touched.
Insulation resistance
The insulation resistance of new, cleaned, repaired windings against the housing and against each
other is > 200
MΩ.
Measurement
The insulation of the windings against the housing for operation voltages up to 400 V must be
measured with 500 V DC. For operating voltages up to 725 V the measurement must be made with
1000 V DC. The temperature of the windings should be 25°C ± 15°C.
Testing
If the minimum insulation resistance of the winding against earth is less than 50 M
Ω
, this may be due
to moisture. The windings must then be dried.
The insulation resistance may reduce after long periods of operation. As long as the measured value
does not fall below the calculated value for the critical insulation resistance of < 50
MΩ, operation of
the motor may continue. If the value is less than this, the cause must be established and if necessary
the windings or parts of the windings must be repaired, cleaned or dried.
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1.3.9 Commissioning
Information
Electromagnetic compatibility
NORD motors comply with the EU-Directive 2014/30/EU. Assembly or installation work must not cause
impermissible interference. Immunity from interference must still exist.
Production of interference: In cases of large differences of torque (e.g. when driving a piston
compressor) a non-sine wave motor current is induced, whose harmonics can cause an impermissible
effect on the mains and therefore impermissible production of interference.
With supply by frequency inverters, various strengths of interference are produced according to the
design of the frequency inverter (type, interference suppression, manufacturer). The EMC information
of the inverter manufacturer must be observed. If a shielded motor supply cable is recommended, the
shielding is most effective if a large area is electrically connected to the metal terminal box of the
motor (with metal EMC cable gland). With motors with integrated sensors (e.g. thermistors)
interference voltages due to the inverter may be produced in the sensor cables.