3.4.5 Power Failure
When connecting the pump to a vacuum chamber, a suitable valve (electric
shut-off valve, for example) needs to be connected on the intake side for
interrupting the intake line so as to prevent the pump from running back-
wards in the event of a power failure. Otherwise the pump may suffer dam-
age.
This valve needs to be controlled (normally closed) from the side of the sys-
tem controller such that the intake line is interrupted in the event of a power
failure. This prevents an uncontrolled flow through the pump.
3.4.6 Operation with a Frequency Converter (FC Operation)
FC operation serves the purpose of reducing the motors switch-on currents
and serves the purpose of adapting the mains frequency to the nominal fre-
quency of the pump.
During operation a frequency ranging from 30 Hz up to the nominal fre-
quency of the pump must be set up. The nominal speed must not be
exceeded. The run-up time to 30 Hz must not exceed 30 s.
As a rule, processing of the output from the temperature sensor in the
motor is mandatory.
Depending on the level and quality of the output voltage from the frequency
converter due to the additional heat produced by the coils, not all operating
conditions may be set up continuously (back pressure and a simultaneous
ambient temperature of 40 °C at maximum load, for example). For this rea-
son, the output from the temperature sensor in the motor must be processed
accordingly.
In connection with FC operation electromagnetic interference will have to be
expected at significant levels. Here the personnel setting up the system must
ensure that the limits laid down in the pertinent standards and guidelines are not
exceeded. In order to reduce the level of electromagnetic interference, shielded
motor cables, shielded cable feedthroughs, motor filters and EMC-compliant
ground connections between FC and pump will be necessary.
Always also observe the information given in the Operating Instructions for
the frequency converter.
NOTICE
NOTICE
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