Vacon CX, Руководство по обслуживанию

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MAIN CIRCUIT Service Manual M4 - M10
29.12.1999 Page 67
8.2.7 Spare Parts
Rectifier module or diode thyristor module.
Contactor, if used
Power terminals, if needed.
Detailed information for the spare parts is available from spare parts lists in
section “SPARE PART LIST”.
8.3 DC bus and precharging circuit
8.3.1 Description
Precharging circuit provides smooth charging for DC capacitors at powering
up a drive by mains. The precharging resistor(s) limits surge current passing
one phase (L3) of charging contactor. Type of the precharging resistors is
thick foil resistor, which is functioning as a fuse in case of excessive current
while precharging procedure. In normal operation, the fuse type precharging
resistors will not open.
The DC capacitor bank filters and stores electrical energy to maintain smooth
and stable DC-energy for a PWM-inverter. Stable voltage in DC bus is
required for proper high performance operation with topology of voltage
source inverter.
Negative feature of the DC capacitors is internal leakage current, through
insulation layer, which variates some amount from individual capacitor to
another. This feature causes variation in voltages divided cross the serial
connected capacitors. To avoid voltage to be concentrated cross the capacitor
with less internal leakage, external balancing resistors are needed. Therefore
balancing resistors / discharging resistors are playing important role by
balancing voltage cross the capacitors connected in serial.
When input energy from front end is disconnected, energy from DC capacitors
has to be discharged down to safe level within reasonable time. The
discharging resistors are now operating such as discharging resistors.
Irpre
Rdis
Rdis
t1
K1
Rpre
Prpre
t1
t0 t1
Udc-bus
t0
t1
Ic
t0
t0
Figure 8.7 Charging circuit by charging contactor