IMPELLER ASSEM 5L8203 - Caterpillar

Illustration 1 g03686278
Line static switch assembly
(1) Static switch snubber board
(2) Static switch driver board
(3) Line static switch thyristors The line static switch assembly is composed of three discrete thyristor modules. One module is connected to each of the input phases. Each module has two devices. In the system, the devices are connected in parallel. However, the devices are connected in opposite directions. The functions of the static switch are as follows:
Isolation of the input node during a discharge
Synchronize signals of the inverter node to the signals of the input node upon restoration of the input signals after an outage
Initial charge of the DC busOne of the parallel sets of thyristors is turned on at a time. The thyristors for all three of the phases only conduct current when the thyristors are forward biased.Line Static Switch Driver Board
Illustration 2 g03686093
(5) Line static switch driver board location
Illustration 3 g03686308
PWA Line static switch driver board (SSD)
The static switch driver (SSD) is located on the right, inside wall of the SIO cabinet on the line static switch assembly. The SSD acts as an interface between the UPS and the static switch.Line Static Switch Driver Board Removal
Refer to Systems Operation, Test and Adjust, UENR4695, "Internal Component Pre-Removal Steps". Perform the internal component pre-removal procedure to shut down the system and to gain access to internal components.
Disconnect thyristors gating leads.
Unplug connectors J1 (ribbon cable) and J3 (24 V). Note: Always practice electrostatic discharge (ESD) prevention when handling printed wire assemblies (PWAs).
Use the following steps to remove the board from the eight white plastic stand-offs. Note: The board must be removed from the stand-offs without bending the board.
Pinch the head of each stand-off so that the board is not locked but is still attached to the stand-off.
Remove