Transfer Switches

Built Rugged for Long Life, Minimum Maintenance, and Trouble-Free Service

Russelectric builds all its transfer switches for years of reliable, trouble-free operation with a minimum of maintenance. In fact, many Russelectric switches have been in continuous service for over 40 years.

Russelectric transfer switch contacts are segmented and have tungsten arcing tips. All contacts are machined from solid copper — not cast, forged, or stamped. All mechanical assemblies, linkages, and connecting rods are purpose-built and precision-machined in-house. Mechanical linkages are sturdy anodized steel rods — machined, not stamped or riveted — with aircraft-style ball joint fittings.

Bus bar is solid copper, silver plated in accordance with UL and ANSI standards. All bus is formed, cut, and punched before being plated to guarantee the integrity of the silver plating and ensure maximum performance.

Enclosures are fabricated with code gauge steel to meet UL and other applicable standards. All enclosures feature arc-welded seams, extra bracing, and smooth, ground corners. Switches are seismic tested to International Building Code requirements for earthquake compliance.

All transfer switches are thoroughly inspected both mechanically and electrically under simulated operating conditions before shipment.

System Operation

Soft loading systems are utility paralleling systems capable of sustained paralleling. Whereas many load curtailment systems transfer loads from the utility power source to the generator all at once (in 100 milliseconds or less), soft loading systems parallel the two live power sources, allowing a more gradual transfer of loads (up to 20 seconds or longer). This eliminates any momentary dip in voltage and the disruptive effects of block loading. Conversely, retransfer from the generator source to the utility source is accomplished through soft loading.

System specifiers should be aware that soft loading systems usually require utility-approved protective relaying and control measures.

Quick-Break, Quick-Make, High-Speed, Preloaded Transfer | B

All Russelectric transfer switches feature preloaded springs and an overcenter mechanism driven by an electric operator for opening and closing the power contacts. During an open-transition transfer, the contact mechanism is securely locked in position until the overcenter position is reached. The preloaded springs then instantaneously open the closed contacts (quick-break) and instantaneously close the open contacts (quick-make) with a momentary break in between. The quick-break feature provides for rapid full arc interruption, under maximum voltage and amperage. This considerably reduces contact erosion and increases the useful life of the switch.

Rapid and Reliable Arc Quenching | C

The current interrupting chamber of the Russelectric transfer switch consists of parallel steel plates partially surrounding the contacts and enclosed by an insulator. When the contacts open, the induced magnetic field draws the arc into the plates where it is split into a series of smaller arcs and extinguished. The plates also conduct heat away from the arc. (Photo shown with insulating barriers removed.)

Front Connected Control Components and Wiring | D

Control components and wiring can be replaced without removing the transfer switch from its enclosure. Tracing of the electrical circuitry is simplified by the neatly arranged, front-connected, flame retardant, 600-volt SIS switchboard wiring. Heavy-duty control components and contacts are provided to handle switching requirements. All wiring connections are labeled with sleeve-type markers, easily visible from the front of the cabinet.