Transfer Switches: Product Families
A transfer switch moves a load between two power sources, most often the utility and a generator. Automatic transfer switches sense the loss of the normal source and switch by themselves. Manual transfer switches are operated by a person. Bypass-isolation switches add a second path, so the transfer switch can be taken out for service without dropping the load.
Codes and standards shape the choice, since emergency and standby systems each have their own requirements. Buyers usually specify voltage, current, number of poles, whether the neutral is switched, the transition type and the enclosure. When an older unit needs a match, they ask for the series name and rating.
35 product families from 8 manufacturers
Automatic (ATS)
ASCO (Schneider Electric)
ASCO 7000 SERIES
Solenoid-mechanism automatic transfer switch line with a microprocessor controller, sold in open and closed transition versions.
- Rated range
- 30-4000 A, C/E/F/G frames
ASCO (Schneider Electric)
ASCO 300 SERIES
Commercial and light-industrial ATS with field-selectable voltage settings.
- Rated range
- 30-3000 A; voltage field-selectable
ASCO (Schneider Electric)
ASCO SERIES 185
Compact ATS aimed at residential and light commercial standby generator systems.
- Rated range
- 100-400 A
Cummins
PowerCommand OTPC
Contactor-style ATS with PowerCommand digital control.
- Rated range
- 40-4000 A, 3/4-pole; open, closed or programmed transition
Cummins
PowerCommand OTEC
Open or programmed transition ATS with PowerCommand control.
- Rated range
- 40-1000 A, 3/4-pole
Cummins
PowerCommand OHPC / CHPC
Cummins ATS lines for open/programmed (OHPC) and closed transition (CHPC).
- Rated range
- 125-800 A, 2/3/4-pole
Cummins
PowerCommand GTEC
Open or programmed transition ATS carrying IEC and CE labeling.
- Rated range
- 40-2000 A, 2/3/4-pole
Caterpillar
Cat CTS Series
Configurable contactor-type ATS with over-center mechanism and MX250 controller; delayed (CTSD) and closed transition (CTSCT) variants exist.
- Rated range
- 40-4000 A; to 600 VAC
Caterpillar
Cat CTE Series
Configurable contactor-type ATS with MX350 controller supporting open, closed and delayed transition.
- Rated range
- 40-4000 A; to 600 VAC
Caterpillar
Cat CTG Series
Pre-configured contactor-type ATS with MX150 controller; CTGD is delayed transition.
- Rated range
- 40-3000 A, 2/3/4-pole; UL 1008 at 480 VAC
Caterpillar
Cat CTX Series
Small open-transition contactor ATS for residential and light commercial service with MX-60 control.
- Rated range
- 40-400 A
ABB (Zenith)
Zenith ZTX series
Zenith ATS with integrated switch and controller in one unit.
- Rated range
- 30-1200 A, 200-480 Vac
ABB (Zenith)
Zenith ZTG(D) series
Zenith ATS in standard and delayed transition, controller integrated with the switch.
- Rated range
- 30-1200 A, 200-480 Vac
ABB (Zenith)
Zenith ZTG(D) T-series (large frame)
Large-frame Zenith ATS covered by an operation and installation guide.
- Rated range
- 1600-3000 A, 208-480 Vac
Russelectric (Siemens)
RTS-03 ATS
Bypass-capable Russelectric ATS line with 3-cycle closing/withstand ratings, open or closed transition, RPTCS controls.
- Rated range
- 100-4000 A, 480 VAC
Russelectric (Siemens)
RTS30 ATS
Russelectric ATS with 30-cycle and 3-cycle UL 1008 ratings, open or closed transition.
- Rated range
- 100-4000 A, 480 VAC
Russelectric (Siemens)
RTSMV
Metal-clad drawout medium-voltage circuit-breaker ATS.
- Rated range
- 5-15 kV class; amps not stated
Kohler (Rehlko)
KCS / KCP / KCC
Any-breaker-rated ATS in standard (KCS), programmed (KCP) and closed (KCC) transition.
- Rated range
- KCS 30-4000 A; KCP/KCC 150-4000 A; 208-600 VAC
Kohler (Rehlko)
KSS
Specific-breaker ATS in the Kohler line with Decision-Maker controller.
- Rated range
- 40-600 A at 208-600 VAC; 800-1000 A at 208-480 VAC
Siemens
SENTRON 3KC ATSE (3KC6 / 3KC8)
IEC-standard automatic transfer switching equipment built on motorized breakers/switches.
- Rated range
- 3KC6 40-160 A; 3KC8 250-3200 A
Generac Industrial
PSTS
Automatic transfer switch line in contactor, power-frame or molded-case configurations, service-entrance and non-service-entrance rated.
- Rated range
- 100-5000 A (product page)
Bypass Isolation
ASCO (Schneider Electric)
ASCO 7000 SERIES Bypass Isolation (ATB / ACTB / ADTB / ASLB)
ATS combined with manual bypass and isolation so the ATS can be serviced without dropping load; open, closed or delayed transition.
- Rated range
- 150-4000 A across J, H/P and G/Q/S/U frames
Cummins
PowerCommand BTPC
Drawout ATS paired with a manual bypass switch for redundant transfer.
- Rated range
- 150-4000 A, 3/4-pole; open, closed or programmed transition
Caterpillar
Cat ATC Contactor Based Bypass Isolation ATS
Contactor-based bypass isolation ATS letting the transfer mechanism be serviced with no interruption.
- Rated range
- 100-1200 A (contactor models); 120-600 VAC
Caterpillar
Cat ATC Power Breaker Bypass Isolation ATS
Breaker-based bypass isolation ATS, drawout, open or closed transition.
- Rated range
- 200-5000 A; 120-600 VAC; UL 1008 to 3200 A
ABB (Zenith)
Zenith ZBTS T-series
Bypass-isolation ATS with touchscreen HMI and optional dual withdrawable bypass on 100-1200 A.
- Rated range
- 100-3000 A, 200-480 V
Russelectric (Siemens)
RTS-03 Bypass/Isolation
Automatic transfer switch with manual bypass/isolation and mechanical interlocks, open or closed transition.
- Rated range
- 100-4000 A, 480 VAC
Russelectric (Siemens)
RTS30 Bypass/Isolation
Drawout bypass/isolation ATS with 30-cycle and 3-cycle ratings, single or dual operator.
- Rated range
- 100-3000 A, 480 VAC
Kohler (Rehlko)
KBS / KBP / KBC
Mechanically operated bypass/isolation ATS in standard, programmed and closed transition.
- Rated range
- 150-4000 A, 208-600 VAC
Generac Industrial
PSTS Bypass Isolation
ATS plus isolation mechanism and manual bypass switch in contactor, power-frame or molded-case configurations.
- Rated range
- 100-1200 A per product title (page text also cites up to 5000 A)
Manual (MTS)
Caterpillar
Cat CTSM / CTGM
Electrically operated, mechanically held non-automatic transfer switches sharing CTS construction, with source-voltage interlock.
- Rated range
- 40-4000 A, 2/3/4-pole
Siemens
SENTRON 3KC0 (MTSE)
IEC-standard manually operated transfer switching equipment.
- Rated range
- 16-1600 A, 3/4-pole
ASCO (Schneider Electric)
ASCO 300 SERIES Manual Transfer Switch
Manual switch giving a permanent connection point for a portable or temporary generator.
- Rated range
- Ratings not stated
Kohler (Rehlko)
KCS non-automatic control
KCS family is offered with automatic or non-automatic control.
- Rated range
- 30-4000 A, 208-600 VAC
Generac Industrial
PSTS Manual (double throw)
Double-throw manual transfer switch in the PSTS line.
- Rated range
- 100-1200 A
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Ratings and lifecycle notes come from the manufacturer pages linked on each entry.
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