This series is the smallest and lightest of the vacuum contactors, useful up to 400 amps continuous, to 2,000 amps AC interrupt, and with some models, 10 amps DC interrupt. They are designed for medium duty and medium to long life with moderate AC and DC current interrupting capability. Minimum expected mechanical life is generally 50,000 operations to millions of operations depending on type. Electrical life at moderate load currents is close to mechanical life. At highest currents, life can be one to a few thousand operations depending on how close to maximum rating is required.

The HB series has a copper alloy type, very low current chop contact recommended for AC type loads where current zeros occur or DC loads and capacitor discharge, where no interruption is required. It has no DC interruption rating unless a special counter-pulse system is used which creates artificial current zeros across the contacts during contact opening.

The HBDC series uses tungsten contacts. It has a more rapid rate of dielectric recovery enabling it to interrupt up to 10 amps DC without assistance, or more with assistance of only a parallel capacitor/resistor combination used to slow the rate of rise of recovery voltage and minimize transient voltages which could be generated during switching. Capacitors and/or non-linear resistors should be placed across the load. This series is also used for very high speed interruption or crobarring of moderate AC or DC currents within its ratings when driven by a Ross SCR controlled stored energy driver. Contact parting times from 1 to 4 milliseconds and contact closing times from 2 to 6 milliseconds are available with the use of this driver.

See other pages and other brochures on HBF, HBDCF & HAF high speed series and stored energy driver. Two SPDT auxiliary contacts are standard on each model. Additional auxiliary contacts can be ordered.

HB Series


HBDC Series


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

Detailed Information

HA Series

HB & HBDC Series