Caterpillar LEXX0526-03 Benutzerhandbuch

LEXX0526-03  

 

2

 
 
In some non-critical emergency power systems, 
it is possible to disconnect the power feeders 
from the automatic transfer switch and electrically 
isolate the switch for servicing. Yet, there are 
many critical systems where interruption of power 
is not permissible. In hospital communication 
systems, data processing centers, airports, etc., 
power disruption is not permitted. For these 
systems, the use of a bypass-isolation switch 
with the transfer switch is essential and often 
required by code. To meet these requirements 
for the inspection and/or maintenance of 
the transfer switch without power interruption, 
Caterpillar offers the CBTS Series Bypass- 
Isolation Transfer Switch. 
 
Description and Operation 
The CBTS Series Bypass-Isolation Transfer Switch 
consists of two major modules – the automatic 
transfer and the bypass-isolation switch. The 
automatic transfer switch module is the proven 
CTS Series, built in CTS, CTSD or CTSCT 
configuration and constructed for rugged, reliable 
operation. The same components – heavy-duty 
silver alloy contacts, rugged drive mechanism and 
silver plated bus bar interconnections are used 
throughout the CBTS Series. 
 
The bypass section is a basic CTS switch provided 
with a quick make/quick break manual load 
transfer handle and a control/interlock system 
consisting of both mechanical and electrical 
interlocks. The bypass is equipped with normal 
failure sensing and a time delay to start the 
engine automatically if the ATS has been removed 
for service and a failure occurs. The modules are 
mounted in a compact enclosure and completely 
interconnected requiring only the normal source, 
emergency source and load cable connections. 
Once installed, no cables need to be removed 
to isolate the transfer switch module for 
maintenance or inspection. The automatic 
transfer switch may be withdrawn for testing 
or maintenance without disturbing the load. 
 
The transfer switch module has three positions: 
 
1. Automatic: The transfer switch is carrying the 
    load, and the bypass switch is in the open 
    position. This is the normal operating position. 
 
 
 
 
 
 
 

 
 
2. Test: The bypass switch is closed and feeding 
    the load. The transfer switch has control power 
    and may be operated for test purposes via the 
    test switch on the enclosure door. 
 
3. Isolate: The transfer switch is withdrawn from 
    all power and ready for maintenance. The load 
    is served by the bypass switch. 
 
 
The CTS Transfer Switch is installed on a draw-
out mechanism, with electrical and mechanical 
interlocks for secure removal after load bypass. 
The CTS control/logic panel is mounted on the 
enclosure door and connected by a wire harness 
and multi-pin disconnect plugs. The transfer 
switch and/or the control panel may be tested, 
isolated and removed for maintenance without 
load interruption. 
 
The bypass-isolation switch module is the same 
basic design as the transfer switch module and 
thus has the same electrical ratings. Manually 
operated, it features high speed, quick make/quick 
break contact action. The bypass-isolation switch 
has three basic positions: 
 
1. Automatic: Normal bypass contacts open, 
    emergency bypass contacts open. 

 

2. Bypass Normal: Normal bypass contacts 
    closed, emergency bypass contacts open. 

 

3. Bypass Emergency: Normal bypass contacts 
    open, emergency bypass contacts closed. 
 
The CBTS’s design requires no additional load 
break contacts which cause load interruption 
during bypass-isolation functions. The bypass 
isolation switch contacts are out of the system 
current path except during actual bypass 
operation. Therefore, they are not constantly 
exposed to the destructive effects of potential 
fault currents. The normal, emergency and load 
are connected between the automatic transfer 
switch and the bypass-isolation switch through 
solidly braced isolating contacts that are open 
when the transfer switch is isolated. All current 
carrying components provide high withstand 
current ratings in excess of those specified in 
UL 1008 standards.