Product Overview

The OT125F3C is a high-performance manual change-over switch manufactured by ABB, designed for reliable power source selection in industrial, commercial, and residential applications. This 3-pole, non-fusible transfer switch is part of ABB’s renowned OT series and provides a simple yet effective solution for switching loads between two separate power sources, such as mains and generator supplies . With a rated current of 125A and a power rating of 45kW at 400V AC, the OT125F3C is capable of handling substantial electrical loads while ensuring safe and dependable operation .

The OT125F3C features an open transition switching mechanism with a stable OFF position, employing a straightforward I-O-II operating scheme where the handle can be padlocked in the OFF position for enhanced safety during maintenance . The switch is designed for base mounting or DIN-rail installation, with front-operated controls and protected clamp terminals that simplify wiring and improve user safety . Unlike some variants, the OT125F3C does not include the operating handle and shaft as standard equipment, requiring these accessories to be ordered separately . This modular approach offers flexibility for system integrators to select the appropriate operating mechanism—whether direct operation handles, selector handles, or pistol handles—based on the specific application requirements .

 

Technical Specifications

Parameter Name	Parameter Value
Product Model	OT125F3C
Manufacturer	ABB
Product Type	Manual Change-over Switch / Transfer Switch
Series	OT Series / SWITCHLINE Series
Number of Poles	3
Rated Operational Current (AC-21A/22A)	125A up to 690V
Rated Operational Current (AC-23A)	90A at 380-415V
Power Rating (AC-23A at 400V)	45kW
Rated Insulation Voltage (Ui)	750V
Rated Impulse Withstand Voltage (Uimp)	8kV
Rated Short-Circuit Current	3.6kA at 690V
Rated Short-Time Withstand Current (Icw)	2.5kA
Mechanical Durability	20,000 operations
Cable Cross-Section	10 – 70 mm² (copper)
Power Loss per Pole	6.3W
Degree of Protection	IP20 (front)
Mounting Type	Base mounting / DIN-rail
Terminal Type	Screw terminals
Operating Temperature	+40°C maximum
Height x Width x Depth	100 mm x 70 mm x 74 mm
Net Weight	0.9 kg
Country of Manufacture	Finland
Order Code	1SCA105037R1001

 

Main Features and Advantages

Open transition changeover with stable OFF position: The OT125F3C features a simple I-O-II operating mechanism, allowing the user to select between two power sources (I or II) with a stable OFF position in between . This open transition design ensures that the switch breaks the connection to one source before establishing the connection to the other, preventing backfeeding between sources. The OFF position is padlockable, providing a secure isolation point for maintenance activities. The handle operation also supports door interlocking in both I and II positions (and when padlocked), enhancing safety by preventing the enclosure door from being opened while the switch is in operation .

Versatile mounting and configuration: The OT125F3C supports both base mounting with screws and DIN-rail mounting, offering flexibility for different installation scenarios . The front-operated design with protected clamp terminals ensures easy access for wiring while maintaining user safety. The switch is suitable for distribution board installation and fixed mounting, with terminals that accept copper cables ranging from 10 to 70 mm² and a wire stripping length of 18-21 mm for secure connections .

Robust construction and high endurance: With a mechanical durability rating of 20,000 operations and a rated impulse withstand voltage of 8kV, the OT125F3C is built for demanding applications . The rugged construction ensures reliable performance even under frequent switching conditions. The switch’s compact dimensions and lightweight design facilitate integration into control panels and distribution boards, while the NEMA 1 rating indicates suitability for indoor applications where protection against limited dust ingress is required .

Comprehensive accessory ecosystem: The OT125F3C is supported by a wide range of ABB accessories, including various handle types (OHBS series for direct operation, OHBS2AJE011 selector handles, OHB4536E311 pistol handles) and shafts (OX56X120, OXP6X170) that allow customization for specific installation requirements . This modularity enables system integrators to optimize the operator interface for door mounting, panel mounting, or remote operation scenarios.