Static Transfer Switches (STS) are designed to transfer the supply between two independent AC power sources. Unlike traditional automatic transfer switches (ATS), a static transfer switch provides a fast load transfer (typically 1/4 of a cycle), which ensures uninterrupted operation of sensitive electronic equipment. Load retransfer to the preferred input source is virtually instantaneous (typically 0.1 ms).

The basic applications of STS are in automatic systems in the power industry, power supply systems for petrochemical industry, computer and telecommunication centers, automatic and security systems of 'intelligent' buildings as well as other equipment which is sensitive to interruptions in the supply. The excellent overload capability and transfer algorithm enables fast fuse clearance in the event of a short-circuit. As a consequence the voltage immediately returns to normal to supply the other loads. The built-in transient voltage surge suppression system for SCR switches provides additional protection against damage to the supplied equipment.

The static transfer switch consists of two bidirectional thyristor switches for each phase equipped with a control and protection system. The 2 or 4 pole types have an additional neutral line switch. After failure of the preferred source, the STS checks the state of the alternate power source and transfers the load to whichever source provides power within selectable limits.

This transfer can be triggered by disturbance in the preferred source voltage, overcurrent in the source or manual or remote change of the preferred source. With both sources in limits and synchronized (phase error within the acceptable range), manual or remote transfer is performed in less than 200 µs.

Transfers initiated by fault conditions in the preferred source depend on the status of the alternate source. For synchronized power sources with phase error within the limits, transfer to an alternate source is made within 6ms delay. Lack of synchronization causes delay before transfer.
It is possible to set the delay with dipswitches.

 Through their complete life cycle, all GE Power Quality systems are fully supported by service teams which provide world-class, 24x7 preventive and corrective services, training and application expertise.

• Selectable voltage limits for full flexibility to protect equipment against sags, swells and interruptions
• Three redundant power supplies providing maximum reliability
• Fail-Safe CMOS logic for fast and reliable control of the STS
• Easy to install and to operate
• Redundant cooling providing full functionality, even in case of a fan failure
• Surge protection to prevent damage to the STS and the supplied equipment
• Blocked transfer in case of short circuit preventing migration to loads
• Manual bypass for no-break operation of the load during maintenance
• Dry contacts to provide status and alarm information to other control systems
• Rackmounted models for easy integration into other systems
• User friendly control panel for easy operation
• Neutral sized for 200% of nominal current to handle imbalanced loads

•  400Volt phase-to-phase
•  230Volt phase-to-phase
•  50Hz
•  99% efficiency @ 0.8PF

• 25-1000Amp,3 and 4-pole,floor mount
• 25-400Amp,1 and 2-pole,standalone & floor mount
• 25-100Amp,1,2,3 and 4-pole,19 inch rackmountable