GE STS-230-100-2 RM STATIC TRANSFER SWITCH

The basic applications of STS STS-230-100-2 RM are in automatic systems for the power industry, power supply systems for the petrochemical industry, computer and telecommunication centers, automatic and security systems of 'intelligent' buildings, as well as other equipment that is highly sensitive to supply interruption. Its high overload capacity and transfer algorithm enable rapid fuse blow during short-circuits. In consequence voltage immediately returns to its normal value to supply other loads. The built-in transient voltage surge suppression system for SCR switches provides additional protection against damage to supplied devices.

 

STS-230-100-2 RM Standard features:

• Ability to create systems with redundancy (switching between independent electrical supply lines, various UPS devices, and generators)

• Short transfer time (typically 3 ms after line failure)

• Elimination of voltage swells, sags, and interruptions on loads (switch-over)

• Protection against voltage variations out of range

• Switches are controlled by Fail-Safe CMOS Logic

• Internal redundancy for power supply systems and SCR drivers (eliminating failures in single points)

• Easy to install and operate

• Low MTTR (mean time to repair)

• Bypass switches to provide continuous non-break operation during STS maintenance

• Remote switching of power sources

• Status indication of the power supply system and STS

 

STS-230-100-2 RM Operating modes:

Static Transfer Switches are designed for operation in three modes: preferred source mode – selected preferred source supplies the load. The load is transferred to the other source if the voltage of the preferred source is beyond the acceptable range. Automatic retransferring mode – after transferring triggered by disturbances in the preferred line, the load is transferred to the preferred line again with a delay which is set by dipswitches, only if the preferred line is healthy. Manual mode – connections are set manually (not automatically).

 

Principle of operation：

STS-230-100-2 RM Static Transfer Switch consists of two bi-directional thyristor switches (2 for each phase) equipped with a control and protection system. The 4-pole models have an additional neutral line switch. The control system is based on the fail-safe CMOS logic. Input source and output line are protected by transient voltage surge suppression varistors. After failure of the preferred source, the STS checks the state of the alternate power source and transfers the load to the source that provides power of better quality. Many modes of operation and many additional settings are provided to meet site-specific requirements.

Transfer may be triggered by:

• Disturbance of preferred source voltage • Overcurrent in source • Manual change of preferred source • Remote change of preferred source

Transfer is not allowed in the event of:

• Incorrect voltage in the alternate source • Excess output current (in load dedicated STS installation)

Transfer is delayed in the event of:

• No synchronization between preferred and alternate source • Exceeding the phase shift limit between the two sources.

With both sources correct and synchronized (phase error within the acceptable range), manual or remote transfer is performed in less than 200 µs. Transfers initiated by fault conditions on the preferred source depend on the status of the alternate source. For synchronized power sources with a phase error within the limits, switching to an alternate source is obtained within 6 6-ms delay. Lack of synchronization causes a delay before transfer. It is possible to set the delay time with dipswitches (11 ms, 15 ms, 23 ms, or 48 ms). The total transfer time is equal to the sum of 2 ms detection time and the alternate source thyristor delay time (so 13, 17, 2,5, or 50 ms respectively).