Monitoring Relays
Enicstra stocks monitoring relays used to detect and signal abnormal electrical or process conditions before they become equipment failures. Inventory covers voltage monitoring (under/over/window), current monitoring, phase loss/phase sequence/asymmetry, three-phase imbalance, level monitoring for conductive liquids, temperature (PT100/PTC thermistor) monitoring, and insulation monitoring for IT-grounded systems.
Brands carried include Allen-Bradley 813S/814S/Series 700 monitoring, Carlo Gavazzi DPB/DPC/DLA, Phoenix Contact EMD series, Crouzet, Schneider RM/RMP, Siemens 3UG4 Sirius, Omron K8DT and K8AB, ABB CM-series, and Bender insulation monitors. Obsolete monitoring relays — discontinued K8AB first generations, retired EMD-FL, end-of-life CM-PFE — are sourced through our supplier network. Each unit is bench-tested and ships with a 12-month functional warranty.
For an obsolete monitoring relay, send the OEM part number for a quote within 1–2 business days.
Monitoring Relays
Can't Find The Part You Need?
Send us the part number, manufacturer, quantity, and condition — we'll locate it.
Do you stock obsolete monitoring relays?
Yes. Discontinued Allen-Bradley 813S/814S, retired Carlo Gavazzi DPA/DPB, end-of-life Siemens 3UG3, and earlier Phoenix Contact EMD codes are sourced through our supplier network.
What does "fail-safe" mean for a monitoring relay?
A fail-safe (de-energize-on-fault) relay drops its output on a detected fault AND on loss of supply power — so power failure looks the same as a fault, ensuring the protected load is stopped. Energize-on-fault relays do not give this behavior; choose per the application's safety logic.
Can I use a phase monitoring relay on a single-phase supply?
No. Phase sequence and asymmetry detection require all three phases connected. Use a single-phase voltage monitoring relay instead.
How do I set the hysteresis?
For most relays, the hysteresis is either fixed (e.g., 5% of setpoint) or adjustable via a separate dial. Set it wider than the expected normal fluctuation to avoid chatter, narrower than the fault condition you want to catch.
Do I need a transformer for high-voltage monitoring?
For voltages above the relay's direct input range (typically 600 V), yes — use voltage transformers (VTs) appropriately rated and apply the burden requirements to the relay's input.
What is the warranty?
12-month functional warranty. Damage from over-voltage, mis-wiring, or operating outside rated input range is not covered.