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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 | WVM911AH |
| Description | Voltage Monitor Relay; Lo/Hi V, Unbal, Loss, Rev; 400...480V AC |
| Datasheet | Download Datasheet |
The Littelfuse SSAC WVM911AH is a 3-phase voltage monitor for 400...480V AC motors. It protects against low voltage, high voltage, voltage unbalance, phase loss and phase reversal. Sensing: Three-phase delta or wye, no neutral connection; line voltage set to the motor nameplate.
Trip / reset points: low voltage 88-92% of the adjusted voltage / +2% of trip; high voltage 109-113% of the adjusted voltage / -2% of trip; voltage unbalance 2-10% adjustable / 90% of the setting.
Trip delay: 0.25-30 s adjustable (phase loss 200 ms). Restart delay: 0.25-64 min adjustable, after a fault or power loss. Reset: Switch selectable: automatic restart upon fault trip, automatic restart or manual. Diagnostics: 6 LEDs: status and a 10-fault memory readout.
Output: 1 Form C (SPDT), 10 A resistive at 250 V AC; 6 A inductive (0.4 PF) at 250 V AC (isolated). Mounting: Surface Mount - two or four #8 screws, 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.
It operates from -40 to +65 °C and can be stored from -40 to +85 °C. Approvals: UL, CSA, CE; ANSI device 27 / 47 / 59.
| Category | |
| Manufacturer | SSAC / Littelfuse |
| Model | WVM |
| Monitoring Function | Low voltage, high voltage, voltage unbalance, phase loss, phase reversal |
| 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) |
| Low Voltage Trip / Reset | 88-92% of the adjusted voltage / +2% of trip |
| High Voltage Trip / Reset | 109-113% of the adjusted voltage / -2% of trip |
| Voltage Unbalance Trip / Reset | 2-10% adjustable / 90% of the setting |
| Sensing Delay on Power-Up | 3-15 s random start delay |
| Trip Delay | 0.25-30 s adjustable (phase loss 200 ms) |
| Restart Delay (s) | 0.25-64 min adjustable, after a fault or power loss |
| 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) |
| Number of Poles | 1 |
| Output Rating | 10 A resistive at 250 V AC; 6 A inductive (0.4 PF) at 250 V AC (isolated) |
| 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 |