THYRISTOR VALVES

Thyristor switched stages are equipped with single-phase oil cooled and insulated thyristor valves that provide single-cycle transient free switching.  Continuous duty rated valve applications are equipped with transformer cooling fins and fans

The valve tank is constructed of 16 Gauge stainless steel and is equipped with a removable 0.25 inch (6.3 mm) thick stainless steel cover.

The valve is designed with N=1 device redundancy and is furnished with a redundant firing circuit and misfire prevention protection. Valve controls enter the tank via an oil-tight military connector for ease of testing and connection.

Thyristor switched harmonic filter stages utilize thyristor valves to provide "fast" vars for the mitigation of voltage sags and voltage flicker. Due to their high cost, vars associated with power factor correction and harmonic filtering, if required, should use conventional capacitor switches, contactors, or circuit breakers.

Thyristor valves are rated based on voltage, current, BIL, and duty rating.

The Delta Valve configuration utilizes thyristor valves connected in a Delta configuration. Voltage ratings of the valves, reactors, and capacitors are rated based on the system line-to-line voltage rating. Current within the Delta is 57% of the current outside the Delta. Therefore, components within the Delta are rated at 57% of the expected line current. Details of this valve configuration are as follows:

For application on systems with line-line voltages of: 2.4kV – 13.8kV

Valve Ratings:
Transient Current Rating: 600 amps (~20% Duty Cycle)
Continuous Current Rating: 180 amps

The Wye-Grounded valve configuration utilizes thyristor valves connected in grounded-wye configuration. Voltage ratings of the valves, reactors, and capacitors are rated based on the system's line-to-neutral voltage rating. Higher system application voltage ratings are possible with this configuration. Details of this valve configuration are as follows:

For application on systems with line-line voltages of: 2.4kV – 24.9kV

Valve Ratings:
Transient Current Rating: 600 amps (~20% Duty Cycle)
Continuous Current Rating: 180 amps

Restriction: Valve configuration for grounded-wye system only. Resistance-grounded, high-impedance grounded, or Delta systems must use the delta connected valve configuration.