OTPC Transfer switch open and closed transition
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Specification sheet OTPC Transfer switch open and closed transition 40 - 4000 Amp Description OTPC transfer switches are designed for operation and switching of electrical loads between primary power and Standby generator sets. They are suitable for use in emergency, legally required and optional Standby applications. The switch monitors both power sources, signals generator set startup, automatically transfers power, and returns the load to the primary power source when the utility returns and stabilizes. OTPC transfer switches are available with closed transition transfer. By briefly connecting the two sources (for 100 msec or less), the transfer from the alternate source back to the normal source occurs without interruption in the power supply to loads. PowerCommand® control – A fully featured microprocessor-based control with digital display. Controls allow operator to enter settings and make adjustments to software-enabled features easily and accurately. Accommodates up to eight event schedules. Programmed transition – Open transition timing can be adjusted to completely disconnect the load from both sources for a programmed time period, as recommended by NEMA MG-1 for transfer of inductive loads. Advanced transfer switch mechanism – Unique bidirectional linear actuator provides smooth, Continuous transfer switch action during automatic operation. Robust control system design – Optically isolated logic inputs and isolation transformers for AC power inputs provide high-voltage surge protection. Main contacts – Heavy-duty silver alloy contacts with multi-leaf arc chutes are rated for motor loads or total system load transfer. They require no routine contact maintenance. Continuous load current not to exceed 100% of switch rating and Tungsten loads not to exceed 30% of switch rating. Communications capability – The transfer switch is capable of communicating with other transfer switches, SCADA and remote monitoring systems, or Cummins generators utilizing LonWorks® protocol. Easy service/access – Single-plug harness connection and compatible terminal markings simplify servicing. Access space is ample. Door-mounted controls are field-programmable; not tool is required. Complete product line – Cummins offers a wide range of equipment, accessories and services to suit virtually any backup power application. Warranty and service - Products are backed by a comprehensive warranty and a worldwide network of distributors with factory-trained service technicians.

Transfer switch mechanism • Transfer switch mechanism is electrically operated and mechanically held in the source 1 and source 2 positions. The transfer switch incorporates electrical and mechanical interlocks to prevent inadvertent interconnection of the sources. • Independent break-before-make action is used for both 3-pole and 4-pole/ switched neutral switches. This design allows use of sync check operation when required, or control of the operating speed of the transfer switch for proper transfer of motor and rectifier-based loads (programmed transition feature). • True 4-pole...

Transition modes Open transition/programmed: Controls the time required for the device to switch from source to source, so that the load generated voltages decay to a safe level before connecting to an energized source. Recommended by NEMA MG-1 to prevent nuisance-tripping breakers and load damage. Adjustable 0-60 seconds, default 0 seconds. Programmed transition is standard on 150-1200 amp switches, and optional on 1600-4000 amps. Open transition/in-phase: Initiates open transition transfer when in-phase monitor senses both sources are in phase. Operates in a break-before-make sequence....

Control functions Level 1 control (C023) Open transition (in-phase) Open transition (programmed) Utility-to-genset applications Software adjustable time delays: • Engine start: 0 to 120 sec • Transfer normal to emergency: 0 to 120 sec Re-transfer emergency to normal: 0 to 30 min • Engine stop: 0 to 30 min • Programmed transition: 0 to 60 sec Undervoltage sensing: 3-phase normal, 1-phase emergency • Accuracy: =/- 2% • Pickup: 85% to 100% of nominal voltage • Dropout: 75% to 98% of pickup setting • Dropout time delay: 0-4 sec Overvoltage sensing: 3-phase normal, 1-phase emergency • Accuracy:...

Time-delay functions Engine start: Prevents nuisance genset starts due to momentary power system variation or loss. Not included in utilityto-utility systems. Transfer normal to emergency: Allows genset to stabilize before application of load. Prevents power interruption if normal source variation or loss is momentary. Allows staggered transfer of loads in multiple transfer switch systems. For genset-to-genset applications, delays transfer of load from lead to secondary generator. Re-transfer emergency to normal: Allows the utility to stabilize before re-transfer of load. Prevents needless...

UL withstand and closing ratings OTPC transfer switches must be protected by circuit breakers or fuses. Referenced drawings include detailed listings of specific breakers or fuse types that must be used with the respective transfer switches. Consult with your distributor/dealer to obtain the necessary drawings. Withstand and closing ratings (WCR) are stated in symmetrical RMS amperes. MCCB protection Transfer switch ampere WCR @ volts max with specific manufacturers MCCBs 14,000 at 480 14,000 at 600 Special circuit breaker protection Drawing reference Drawing reference These amperages don’t...

WCR @ volts max. with current limiting fuses 200,000 at 480 Max fuse, size and type 200 A Class, J, RK1, RK5, T Drawing reference 600 A Class, J, RK1 or RK5 1200 A Class T 2000 A Class L 600 A Class, J, RK1 or RK5 1200 A Class T 2000 A Class L 3-cycle ratings Transfer switch ampere 300, 400, 600 WCR @ volts max 3 cycle rating 25,000 at 600 Drawing reference

Transfer switch lug capacities All lugs are 90°C rated and accept copper or aluminium wire unless indicated otherwise. Cables per phase Two hole lug, one accepts 3/0 AWG – 600 MCM and the other accepts #4 AWG – 250 MCM # 2 AWG to 600 MCM, standard (Feature N045) 1/0 AWG to 750 MCM, optional (Feature N066) Compression Lug Adapter, optional (feature N032)** **Recommended Compression lugs (½” stud , 1-3/4” centers) Lug mounting hardware included 750 MCM THOMAS & BETTS