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Cooling circuit, Chill blocks, Coolant pumps – Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C-Frame) - ForGe Control User Manual

Page 329: Cooling circuit chill blocks coolant pumps

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Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014

329

Component Definition and Maintenance

Chapter 5

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 275 - Chill Block Assembly

Coolant Pumps

Two pumps (P1 and P2) are used to move coolant through the system
(

Figure 276

). 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