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7.2
Switching on
Measures for start-up
After installation or inspections, the following measures are recommended for normal start-
up of the machines:
● Start the machine without a load. To do this, close the circuit breaker and do not switch
the machine off prematurely. Switching the machine off again while it is starting up and
still running at slow speed should be kept to a bare minimum, for example for checking
the direction of rotation or for checking in general. Allow the machine to run to a standstill
before switching it back on again.
● Check mechanical operation for noise or vibration at the bearings or end shields.
● If the machine is not running smoothly or is emitting abnormal noises, switch it off, and
determine the cause of the fault as it runs down.
● If mechanical operation improves immediately after the machine is switched off, then the
cause is magnetic or electrical, e.g. voltage imbalance, magnetic imbalance. If
mechanical operation does not improve immediately after switching the machine off, then
the cause is mechanical, e.g. an imbalance in the electrical machines or in the driven
machine, inadequate alignment of the machine set, operation of the machine with the
system resonating (system = machine + base frame + foundations etc.).
● If the machine runs perfectly in terms of its mechanical operation, switch on any cooling
devices present and continue to monitor the machine for a while as it idles.
● If it runs perfectly, connect a load. Check that it runs smoothly.
Read off and document the values for voltage, current, and power.
Where possible, read off corresponding values for the driven machine and document
them as well.
● Monitor the bearing temperature, winding temperature, etc. until the system reaches a
steady state.
Document these, provided this is possible with existing measuring instruments.
● Start the machine without a load; to do this, close the motor starter protector and do not
switch the machine off prematurely.
● You should limit how often you switch the machine off while it is starting up and still
running at a slow speed, for checking the direction of rotation or the required dimensions,
for example.
● Allow machines to reach a standstill before switching them back on.
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Operating Instructions, 03/2018, A5E41926185A
Start-up
7.2 Switching on
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