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4.6.
FAN MOTOR UNIT
4.6.1.
Electric motors
Before start-up:
- Inspect the motor control board and check that the
motor protection devices are sized for the maximum
amperage. corresponding to the rated value on the plate.
If the protection devices are sized for an amperage in
excess of the rated value, you must make sure that the
working range is sufficient.
- The thermistors (operating voltage 1 V) must not be
connected to the electric motor power supply line, as
otherwise they would be irreparably damaged
- Check that the mains supply voltage is suited to that of
the motors as indicated on the relevant plates.
4.6.1.1. Connection for direct starting
The simplest electric motor start—up system is obtained
by connecting the motor direct to the power supply.
However, this method has limitations due to the high
start-up current (pick-UD); this type of start-up is
recommended for power ratings of up to 5.5 KW at which
TCF installs 4 pole, 220/380 V three—phase motors as
standard.
The wiring diagrams are shown in fig. 27.
4.6.1.2. Connecting with delta—star starter
If the motor start-up current exceeds the value permitted
by the power supply you may decide to opt for delta-star
starting.
For this purpose TCF installs dual voltage 380/660 V
motors on its Air Treatment Units starting from an output
of 7.5 KW, thereby allowing the motor to function
normally at 380 V (delta connection) and to start-up at
660 V (star connection).
This arrangement reduces the starting current to
approximately 30% of the current involved in the case of
direct starting.
13
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