Overview#
The Thomson TS880 is Thomson Power Systems' mission-critical automatic transfer switch, covering 800A to 4000A with insulated-case power switching devices. Available in both 3-cycle and 30-cycle withstand configurations, it serves data centers, hospitals, and facilities where power continuity and selective coordination are non-negotiable.
The TS880 uses the TSC 900 controller as standard — a 7-inch color touchscreen with front-panel programming, comprehensive event logging, and Modbus communication. All configurations (open, closed, soft-load, bypass-isolation, service entrance, dual source) are available across the full 800-4000A range. The 30-cycle design shares its platform with Thomson's UL 1558 low-voltage power circuit breaker switchgear.
Withstand current ratings#
3-Cycle models (standard):
| Frame | @240V | @480V | @600V |
|---|---|---|---|
| 800-4000A | 100,000A | 100,000A | 85,000A |
30-Cycle models (insulated-case):
| Rating | @240V | @480V | @600V | 30-Cycle (all voltages) |
|---|---|---|---|---|
| 3-Cycle | 85,000A | 85,000A | 85,000A | — |
| 30-Cycle | — | — | — | 65,000A |
For switching devices without trip units, withstand is 65,000A at both 3-cycle and 30-cycle.
Enclosure dimensions#
ATS only (NEMA 1):
| Frame | H x W x D (in) | Weight |
|---|---|---|
| 800-2000A | 91.5 x 36 x 42 | 1,500 lbs |
| 2500A | 91.5 x 36 x 60 | 1,800 lbs |
| 3000/3200A | 91.5 x 36 x 60 | 2,000 lbs |
| 4000A | 91.5 x 48 x 72 | 3,000 lbs |
ATS with bypass-isolation (NEMA 1):
| Frame | H x W x D (in) | Weight (3P / 4P) |
|---|---|---|
| 800-2000A | 92 x 72 x 66 | 3,200 / 3,800 lbs |
| 2500-3200A | 92 x 72 x 66 | 3,600 / 4,250 lbs |
| 4000A | 92 x 96 x 90 | 6,500 / 7,500 lbs |
The bypass-isolation 4000A unit weighs up to 7,500 lbs — verify floor loading capacity and access routes before specification.
Bypass-isolation: how it works#
The TS880 bypass-isolation uses draw-out transfer power switching devices with key interlock mechanisms, mounted in separate barriered compartments from the ATS. The procedure:
- Transfer load to the preferred source via the bypass handle
- Isolate the ATS from both sources using the key interlock mechanism
- Draw out the transfer switching devices for inspection or replacement
- Service contacts, mechanisms, and controller with the load running on the bypassed source
- Return draw-out switches, release interlocks, and return to automatic operation
The break-before-make bypass design prevents utility and generator paralleling under any circumstance. For units with closed-transition capability, the bypass can be operated in make-before-break sequence at the operator's direction.
Closed transition and soft-load#
The TS880 CTTS uses electrically interlocked insulated-case power switching units with the TSC 900 controller's built-in sync check relay. The controller monitors voltage differential and slip frequency between sources. When both are within threshold, it initiates a closed transition lasting less than 100ms. If the paralleling timer exceeds its limit, extended paralleling protection opens the other source within 500ms.
Soft-load transition is available as an additional ordering option for process loads requiring gradual transfer ramping.
Our service experience#
We service Thomson TS880 units in Bay Area data centers and healthcare facilities. The insulated-case switching mechanism is extremely robust at these current levels — contact life far exceeds contactor-based alternatives in this amperage class. Annual thermographic scanning under load is essential for all frames, not just the larger ones — at 800A+, any loose busbar connection generates significant heat.
The 4000A bypass-isolation units are physically massive — at 92" x 96" x 90" and up to 7,500 lbs (4-pole), they require rigging equipment and careful access planning. We've seen installation delays on retrofit projects where the freight elevator couldn't accommodate the weight or dimensions. Specify access requirements during design to avoid costly field surprises.
The TSC 900 touchscreen controller is a significant upgrade from the TSC 7320 used on the TS870. The 7-inch color display makes programming and troubleshooting faster during service calls, and the event logging with time/date stamps provides valuable forensic data when investigating transfer events.