Trane Starters User Manual

CTV-PRB004-EN 53
Electrical System—Design Guidelines
Medium-voltage disconnect
All medium-voltage starters have an isolation switch as standard.This switch is a non-load-break
switch that is not designed to be opened under load, i.e. while the chiller is operating. All medium-
voltage starters have a mechanical interlock to prevent opening the isolation switch while the main
contactor is closed and the compressor is running.
In order to open the medium-voltage compartment door, the compressor must be turned off before
the isolation switch can be opened.Then the isolation switch stabs can be separated from the
medium-voltage bus. Baffles slide over the stab slots and the medium-voltage bus is completely
isolated behind shielding panels. Now the medium-voltage compartment door can be opened
safely. After servicing, the medium-voltage compartment door must be secured before the
isolation switch can be closed.
If there is a requirement to be able to open the circuit while under load, a load-break disconnect
switch may be furnished as a special option on medium-voltage starters.The load-break switch is
mounted in an additional section of the starter-cabinet assembly. See Figure 41 and Figure 42 for
a comparison of the two options. A switch spring is loaded, or “charged,” as the handle is moved.
When spring pressure is sufficient, a device releases the switch mechanism.The spring loading
provides a rapid, positive opening and closing of the contacts.
Note: Medium-voltage circuit breakers are not available throughTrane.
Short-Circuit Interruption
Low-voltage short-circuit interruption
When a circuit breaker is specified, it serves both as the short-circuit interrupt protector and the
disconnect switch. Unlike the non-fused disconnect, a circuit breaker does have an interrupting
rating. Because a circuit breaker is constructed to safely interrupt the high level of current caused
Figure 41. Isolation switch Figure 42. Load-break switch
incoming line power
outgoing load power
Low
Volts
isolation
switch
incoming line power
outgoing load power
Low
Volts
isolation
switch
load-break
switch
load-break
switch section
X-Line starter
CTV-PRB004.book Page 53 Sunday, December 18, 2011 6:39 PM

Trane Starters Specifications

General

Brand	Trane
Model	Starters
Category	Chiller
Language	English