KAESER EPC 1000-2-500, Service Manual, Page: 47 / 110

7.4 Motor protection
The machine should only be operated with a correctly adjusted motor overload protection switch to
protect the motor from overloading.
A motor overload protection switch that is set too high provides no protection. Incorrect setting can
lead to irreparable damage.
7.4.1 Motor protection setting
In the star-delta configuration the phase current is fed via the motor overload protection device. This
phase current is 0.58 times the rated motor current (see motor nameplate).
The motor overload protection switch setting can be 10 % higher than the rated phase current
to prevent it from being triggered by voltage fluctuations, temperature influences or component
tolerances.
➤ Switch the machine on from the control unit.
The machine is shut down by the motor overload protection switch?
➤ Contact KAESER
Service.
7.5 Checking direction of rotation
The machine is designed for a clockwise phase sequence.
Ideally, the direction of phase rotation should be measured with a phase sequence meter. Alterna‐
tively, start the machine very briefly and observe the direction of rotation of the motor cooling fan.
1. Check the direction of phase rotation with a phase sequence meter.
2. If the direction is incorrect, reverse supply phases L1 and L2.
You have no phase sequence meter?
➤ Switch the machine on and off again the moment the drive motor begins to turn.
➤ Check the direction of rotation against the arrow on the fan cowl.
➤ If the direction is incorrect, reverse L1 and L2.
7.6 Starting the machine for the first time
Precondition No personnel are working on the machine
All panels are in place and secured
1. Open the shut-off valve to the air network.
2. Switch on the power supply isolating device.
The machine switches to LOAD and delivers compressed air.
➤ Watch for any faults occurring during the first hours of operation.
Carry (or have carried) out the following tasks after the first 50 operating hours:
■ Check that all electrical connections are tight.
■ Change the compressor oil.
7 Initial Start-up
7.4 Motor protection
No.: 9_9431_02 E
Service Manual 2-stage piston compressor
EPC
37