HBF, HAF & HBDCF Series 
The high speed vacuum contactor and relay series consists of selected types of vacuum contacts and actuators specially designed with low inertia and high shock resistance to allow contact parting times from 1 to 6 milliseconds and contact closing times from 2 to 12 milliseconds. Maximum speed is attainable in conjunction with a Ross Engineering SCR controlled stored energy solenoid driver. Actuator solenoid resistance and inductance is carefully matched with the stored energy level to provide the highest speed, yet reasonable mechanical life. Expected mechanical life is generally 5,000 to 50,000 operations at the highest speeds. The highest speed models in the series have somewhat reduced voltage and current ratings compared to similar standard Ross vacuum contactors. Contact travel and over-travel is reduced to a minimum to attain highest speed with short mechanism travel.


Standard units are available with operating voltages from 5kV to 190kV AC PK or DC, with peak test voltage to 300kV PK, continuous currents to 1,200 amps and interrupt currents to 28,000 amps. Capacitor discharge closing currents up to 100,000 amps are possible depending on time constant of discharge down to 37% level.

With repeated high speed DC interruptions or crobar type operations in DC circuits, both transformers and loads must be protected from possible transient over-voltages and inrush currents. Transformers must be well braced and end turns especially well insulated. Loads, especially inductive loads, must have capacitance and/or non-linear resistance in parallel at their terminals and on the output terminals of the transformer. Capacitors with at least 1.5 times voltage rating (in the order of .01 to 0.25 mfd) in series with 1 to 2 ohms per kV, are recommended. GE Thyrite or similar nonlinear resistance carefully rated for appropriate operating current is also helpful. To limit inrush on re-energizing after a crobar has tripped a primary breaker, a dual step-start contactor or circuit breaker is recommended. See Three Pole HV Vacuum Contactors / Circuit Breakers for further power control information.

Two auxiliary SPDT contacts are standard on each model. Additional auxiliary contacts can be ordered. 


Specifications are for reference only and are subject to change.
Contact Ross Engineering Corp. for current information.

Detailed Information

HA Series

HB & HBDC Series