nord 6051302, Operating And Assembly Instruction Manual

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Motors – Operating and Assembly Instructions
20 B 1091 en-2722
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1.3.9 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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1.3.10 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.
Interference immunity: For motors with integrated sensors (e.g. thermistors) the operator must ensure
adequate immunity to interference by the selection of a suitable sensor cable (possibly with screening,
with connection as for the motor supply cable) and evaluation device. The information and instructions
in the operating instructions for the inverter and all other instructions must be observed before
commissioning. After installation of the motor, it must be checked for correct functioning. In the case of
brake motors, the correct function of the brake must also be checked.