Beckman Couler ALLEGRA X-12/R, Руководство по обслуживанию, Страница: 59 / 83

Section 4: Schematics
Power Module
The Power Module contains six IGBTs forming a three-phase bridge circuit, a Brake
Drive IGBT, a full wave bridge rectifier, and a thermistor for monitoring heat sink
temperature.
Fault Detection
Besides the fault detection provided by the IGBT driver, the current through the IGBT
bridge is monitored by U12 & 13. If the current should exceed 20 amperes the drive fault
signal will activate, disabling the IGBT drive. Also the thermistor within the power
module is monitored and the fault signal activated if the maximum temperature of the
module is exceeded. The drive over temperature status line is also activated.
Indicators
There are three LED indicators on the MDB. LD1 is green and indicates that the drive is
enabled. LD2 is red and indicates that the fault signal is active. LD3 is yellow and
indicates that high voltage is present. It should be noted that dangerous voltages are
present on the MDB while LD3 is illuminated. It will remain illuminated after power is
removed until the HVPS discharges.
Normal Operation
Before a run is made, only the yellow LED is illuminated. When the run begins both the
yellow and green LED's are illuminated. The green LED is extinguished at the end of the
run. The red LED should never be illuminated. Also, the Brake resistor will get hot
during deceleration and is electrically connected to the HVPS. Therefore contact with the
Brake Resistor should be avoided.
4-4 Allegra X-12 Service Manual 7/04