Single phase VOLTAGE sensing relays are offered in the following versions:



VOLTAGE MONITORS are used in AC and DC circuits. Many of our single phase monitors can be used in either.

Some can be used to monitor voltages up to 600vac; but Potential Transformers (PT's) can be used to step the voltage down without compromising performance for those models that might correspond to the features you're looking for but are limited to sensing lower voltages. We also offer medium voltage PT's to 15 kV.

M Series   DIN Rail & Surface Mtg



H.89 W.17.5 D.59(mm)

Function Under Voltage Timed Multi Function Under Voltage Under or Over Voltage Under or Over Voltage
  (Delayed Restart) Voltage DC Voltage 7 ranges (2-500VAC/DC)
Time Delay (from fault) 100mS 100mS or 1S 0-30 sec 0.2 - 10 sec + 5% 0.2 - 10 sec + 5%
Hysteresis ~2% 2% or 10% of set point ≈5% of set point ≈2% of set point 2% or 10% of set point
Latch - Switch Selectable _ - Switch Selectable
Output SPDT Relay SPDT Relay SPDT Relay 2 x SPDT Relays SPDT Relay
Output Rating 6A @ 250VAC 8A @ 250VAC 8A @ 25V DC1 5A @ 250VAC 10A @ 250VAC
Supply Voltage Un 220VAC 18-240VAC, 12-240VDC monitors own supply monitors own supply 24–230 / 12–60V AC/ DC
Integral Transformer - Yes _ - -
Monitoring Range 70 - 110% Un

1 to 26.5VAC/D

10 to 265VAC/DC

Switch Selectable

9 - 28VDC


LV model 70 - 260

HV model 140 - 300

2 – 20,

5 – 50,

10 – 100,

20 – 200,

50 – 500V

Switch Selectable

45 Series   DIN Rail Mtg


H.78 W.45 D.99(mm)

Model No
Function Over Voltage
Time Delay (from fault) 0.1-3S
Hysteresis 5-50%
Latch User Selectable
Output SPDT Relay
Output Rating 10A @ 250VAC
Supply Voltage Un 24, 110, 230VAC
Integral Transformer Yes
Monitoring Range

Y2: 0.5-10VAC/DC

Y3: 3-60VAC/DC

Y4: 30-600VAC/DC

B1 Series   11 Pin Plug-In


H.80 W.40 D.92 (mm)

Model No
Function Under Voltage Over Voltage
Time Delay (from fault) ~1S ~1S
Hysteresis ~1% ~1%
Latch No No
Output SPDT Relay SPDT Relay
Output Rating 8A @ 250VAC 8A @ 250VAC
Supply Voltage Un 12, 48VAC/DC, 24VDC 12, 48VAC/DC, 24VDC
24, 110, 220/240VAC 24, 110, 220/240VAC
Integral Transformer 110, 220/240V only 110, 220/240V only
Monitoring Range 3.5-50V or 5-70VDC 3.5-50V or 5-70VDC
35-500VAC or 50-700VDC 35-500VAC or 50-700VDC