Operating instructions

59
9.3.2 - The compressor power variable-frequency drive
The compressor power variable-frequency drive cabinet
includes the following functional components (identified in
accordance with the references on the wiring diagram):



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1. Circuit breaker/main disconnect switch (QF101) for the following functions:
- short-circuit protection of the main circuit
- single connection point of the installation power cables
- isolation and shut-down of the machine, using the handle accessible on the
outside of the control box
- emergency stop, initiated by the PIC III control
2. Filter CEM RFI (ZGS) to limit high-frequency conductor interferences (>150
kHz).
3. Surge limiter (F).
4. Power supply circuit protection disconnect switch for the PIC III control box
(QF).
5. Power transformer (T1) and fuse (FU10) for the internal control circuit of the
variable-frequency drive.
6, Inductance inputs of the main circuit (LF).
7. Capacitor resistors (R1-3C) and coils for inlet ltering of the main circuit
8. Load resistors of the main power circuit (R4-6C) and protection fuses of the
load circuit (FU**). To limit the inrush current while power is supplied to the
variable-frequency drive
9. Load resistor shunt capacitors (K1-). They short-circuit the load resistors when
the capacitors are loaded.
10. Power module and associated control interface board (GS) for the following
functions:
- compressor start-up and shutdown by voltage/frequency ramping to permit
limitating of the couple and inrush current at start-up
- control of the voltage/frequency applied to the compressor
- all electrical compressor protection devices
- all devices to protect against internal faults of the variable-frequency drive as
well as pressure safety switch cut-out and re-starting the oil pump
- report of variable-frequency drive status parameters and internal faults to the
PIC III control
11. Acquisition and measurement interface board (A3). Isolates and conditions the
voltage measuring and temperature signals reported to the power module
12. Communication gateway board. Provides the communication interface between
the variable-frequency drive and the PIC III control.
13. Internal cooling fan(s) (EV10-).