Standard Model
for Fixed Trip Setting


Trip point set with external selected resistor(s) for: 

  • Internal line or external source sensing.
  • Internal trip range set (1V to 200V available).
  • Sense polarity set + or AC, - optional.
  • Power 115V AC non-isolated, common ground and neutral.
  • Isolated inputs & outputs also available.

Set point repeatability 1% AC, 0.1% DC.

Temperature range -10°C to 55°C.

Basic reset time 100 milliseconds.

Over-voltage withstand 200V to 2500V PK transient impulse, depending on model. 

Output drives average 115V relay coil. Internal trip basic input resistance 78kΩ, 55V PK. Add external resistor for external trip sensing and omit R2.  0.7mA DC or AC PK into 78kΩ basic input to develop 55V DC or 39V RMS AC sense voltage across 78kΩ, ½ watt input resistor to trip. Sense voltages 1V to 200V available.

For adjustable trip, hysteresis, delay, isolated input, see Deluxe Model.

For internal 115V AC line sensing, select resistance of R2 for desired operating point. ie...

  • For internal 100V AC RMS trip use 122K ½ watt for R2.
  • For internal 39V AC RMS or 55V DC or AC PK trip use 0 ohms for R2.
  • For external 1000V AC RMS or 1414V AC PK trip use 1.92M 2 watts for R3 if R1 is 78K, omit R2.
  • For external +1000V DC trip use 1.35M 2 watts for R3 if R1 is 78K, omit R2.
  • For external +10,000V DC trip use 14.1M 20 watts for R3 if R1 is 78K, omit R2.
  • For external 100,000V DC trip use 142M 200 watts for R3 if R1 is 78K, omit R2.
  • 78K R1 is basic internal resistor for line sensing. To reduce external HV resistor wattage internal R1 can be increased to reduce required sensing current and external resistor wattage. Also internal sensitivity can be changed for very low sensing voltages.
  • For external sense select resistance of R3 and omit R2.

 Standard Model

Deluxe Model

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