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APCMON2 Heater Load & Solid State Relay Monitor

The APCMON2 monitors the condition of a solid state relay and it's load circuit. The APCMON2 mounts directly on top of the input and output terminals of most industry-standard solid state relays and monitors the input signal and output voltage to detect a shorted SSR, open heater/load, loss of AC mains supply, and DC input power.

Standard  Features:

  • Monitors the heater load and solid-state relay for fault conditions

  • Detects open load, shorted SSR output, loss of AC mains and DC input/control voltage

  • Compact design mounts directly to most industry-standard solid-state relays

  • LED output indictator

  • 5-26Vdc control input

  • 100-600Vac, 50/60Hz load-voltage range

  • 4000Vrms isolation voltage

  • Requires an external 10-26Vdc power supply

Ordering Information:  Part Number - APCMON2

Input Specifications:

Part Number


Power Supply Voltage Range (Vdc)

Control Input (Vdc)



Control Input Impedance (Ohms)

Load Sense Input Voltage Range (Vac; 50/60Hz)

Input-to-Line Isolation Voltage (Vrms, 25°C for 1 second)

Maximum Off-State Blocking Voltage (Vpk for 1 minute)

Maximum Off-State Leakage Current (RMS)






200mS (with control input off)
750mS from last off-cycle (1 sec cycle time 50% duty cycle)
2.5 Sec from last off-cycle (1 sec cycle time 95% duty cycle)
Up-to 15 seconds when using the interrupted Input

Response Time

Alarm Output Specifications:

Relay contact maximum rating = 0.05A / 48Vdc (resistive loads only)
Contacts open upon fault or loss of power.
Contacts are closed when no faults are present.

General Specifations:



Operating Temperature Range

Storage Temperature Range

-0 to +50 °C

-40 to +100 °C

Dimensions & Signals

Continuous Mode: The control input is wired to the standard IN- and IN+ of the SSR input terminals for continuous
mode operation.
Interrupted Mode: The control input is wired to the IN- of the SSR and the INT IN+ of the APCMON2. Interrupted
mode provides a brief off signal of 150mS every 15 seconds to test the input to output logic of the relay.


*Notes: To reliably detect an open load, the load current must drop below 60uA when the load is opened. Any
residual leakage in the wiring or load break may cause the APCMON2 to not be able to detect the open load
condition. Using the APCMON2 with an SSR that has an on-board snubber will improve the reliability of the
detection because it will present a lower impedance to the load circuit and raise the 60uA detection threshold to a higher value, typically around 300uA. If that threshold is not high enough, a power resistor or external R-C snubber (0.47uF/100R) may be added in parallel with the SSR output. The resistor or snubber should be chosen so that when the load is open, the voltage across the SSR drops below 20VAC.


Anacon Power & Controls

100 Powder Mill Rd. Suite 162

Acton, MA 01720


TEL: 800-466-9080
TEL: 978-287-0715


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