Rockwell Automation Allen-Bradley PowerFlex 7000, Руководство пользователя, Страница: 330 / 434

330 Rockwell Automation Publication 7000L-UM301F-EN-P - March 2020
Chapter 5 Component Definition and Maintenance
Cooling Circuit
This circuit is required to cool such devices as Silicon Controlled Rectifier
(SCR), Symmetrical Gate Commutated Thyristor (SGCT), snubber resistors
and sharing resistors. The SCRs and SGCTs are positioned between two chill
blocks in an alternating fashion to create a horizontal stack. The sharing and
snubber resistors are mounted on a plate with cooling tubes embedded within.
As cool liquid flows through the cooling tubes the entire plate is cooled, which in
turn cools the resistors.
Chill Blocks
The chill blocks are constructed of highly conductive copper machined parts that
are silver soldered together. The parts are machined to a fine surface finish. The
copper chill block provides good heat transfer from the electrical device to the
chillblock. The coolant system is connected to each chill block with flexible
10 mm (3/8-in.) hose which fits onto stainless steel hose barbs which are part of
the chill block assembly.
Figure 276 - Chill Block Assembly
Coolant Pumps
Two pumps (P1 and P2) are used to move coolant through the system
(
Figure 277 ). One of the pumps is used as a backup. The control logic alternates
the primary and secondary pump to ensure equal time of operation. Ensure that
the pumps never run dry, as this will damage the pump seals. Ensure the pumps
are not excessively noisy (pumping air pockets) when filling the system.
Plate with Cooling Tubes
Chill Block
Coolant H