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To ensure accuracy, please note that images may be representative. Refer to the product data sheet for detailed specifications.
| Manufacturer | SSAC / Littelfuse |
| Manufacturer Product Number | WVM911AN |
| Description | Phase Monitor Relay; Lo/Hi V, Unbal, Loss, Rev; 3; 400...480V AC; Restart 6-300s |
| Datasheet | Download Datasheet |
The Littelfuse SSAC WVM911AN is a phase monitor relay with 1 Form C (SPDT) output and rated 10 A resistive at 250 V AC; 6 A inductive (0.4 PF) at 250 V AC (isolated), driven by a 400 to 480V AC input.
It watches all three phases for low voltage, high voltage, voltage unbalance, phase loss, phase reversal, measuring three-phase delta or wye, no neutral connection; line voltage set to the motor nameplate.
The undervoltage trip point covers 88-92% of the adjusted voltage.
It drops out 200 ms after a lost or reversed phase and re-energises 6-300 s adjustable, after a fault or power loss after the fault clears.
Reset is switch selectable: automatic restart upon fault trip, automatic restart or manual.
It has Surface Mount - two or four #8 screws mounting and Screw terminals with captive wire clamps, up to #12 AWG terminals.
| Category | |
| Manufacturer | SSAC / Littelfuse |
| Model | WVM |
| Monitoring Function | Low voltage, high voltage, voltage unbalance, phase loss, phase reversal |
| Number of Phases | 3 |
| Sensing Method | Three-phase delta or wye, no neutral connection; line voltage set to the motor nameplate |
| Input Voltage | 400...480V AC |
| Input Operating Range | 400-480 V AC, 50/60 Hz (selectable nominal) |
| Undervoltage Trip Range | 88-92% of the adjusted voltage |
| Overvoltage Trip | 109-113% of the adjusted voltage |
| Phase Unbalance Trip | 2-10% adjustable; phase loss at 15% or more |
| Restart Delay (s) | 6-300 s adjustable, after a fault or power loss |
| Trip Delay - Phase Loss and Reversal (ms) | 200 ms |
| Trip Delay - Unbalance | 0.25-30 s adjustable |
| Reset Method | Switch selectable: automatic restart upon fault trip, automatic restart or manual |
| Status Indicator | 6 LEDs: status and a 10-fault memory readout |
| Contact Configuration | 1 Form C (SPDT) |
| Output Rating | 10 A resistive at 250 V AC; 6 A inductive (0.4 PF) at 250 V AC (isolated) |
| Number of Poles | 1 |
| Mounting Type | Surface Mount - two or four #8 screws |
| Termination Style | Screw terminals with captive wire clamps, up to #12 AWG |
| Dimensions | 111.8 x 175.3 x 61.0 mm (4.4 x 6.9 x 2.4 in), H x W x D |
| Operating Temperature (Storage) | -40...+65 °C (-40...+85 °C) |
| Approvals | UL, CSA, CE; ANSI device 27 / 47 / 59 |