Get A Quote
My Account
To ensure accuracy, please note that images may be representative. Refer to the product data sheet for detailed specifications.
| Manufacturer | Symcom / Littelfuse |
| Manufacturer Product Number | 355-600 |
| Description | Voltage Monitor Relay; Lo/Hi V, Unbal, Loss, Rev; 475-600 VAC; TD 2-30s adj |
| Datasheet | Download Datasheet |
The Littelfuse SymCom 355-600 is a 3-phase voltage monitor for 475-600 V AC motors. It protects against low voltage, high voltage, voltage unbalance, single-phasing and phase reversal.
Trip / reset points: low voltage 90% / 93% of setpoint (±1%); high voltage 110% / 107% of setpoint (±1%); voltage unbalance 2-8% adjustable / trip setting minus 1% (5-8%), minus 0.5% (2-4%) (NEMA).
Trip delay: 2-30 s adjustable (low/high voltage and unbalance); 2 s (single-phasing, >25% unbalance). Restart delay: Manual or 2-300 s adjustable (after a fault or a complete power loss). Reset: Manual or automatic. Diagnostics: Diagnostic LEDs: overvoltage, undervoltage, voltage unbalance, reverse phase, normal.
Output: 1 Form C (SPDT). Mounting: Surface mount (#8 screws). Dimensions: 74.42 x 133.86 x 74.93 mm (2.93 x 5.27 x 2.95 in), H x W x D.
It operates from -40 to +70 °C and can be stored from -40 to +80 °C. Approvals: UL 508.
| Category | |
| Manufacturer | Symcom / Littelfuse |
| Model | 355 |
| Monitoring Function | Low voltage, high voltage, voltage unbalance, single-phasing, phase reversal |
| Input Voltage | 475-600 VAC |
| Low Voltage Trip / Reset | 90% / 93% of setpoint (±1%) |
| High Voltage Trip / Reset | 110% / 107% of setpoint (±1%) |
| Voltage Unbalance Trip / Reset | 2-8% adjustable / trip setting minus 1% (5-8%), minus 0.5% (2-4%) (NEMA) |
| Trip Delay | 2-30 s adjustable (low/high voltage and unbalance); 2 s (single-phasing, >25% unbalance) |
| Restart Delay (s) | Manual or 2-300 s adjustable (after a fault or a complete power loss) |
| Repeatability | ±0.1% (fixed conditions) |
| Reset Method | Manual or automatic |
| Status Indicator | Diagnostic LEDs: overvoltage, undervoltage, voltage unbalance, reverse phase, normal |
| Contact Configuration | 1 Form C (SPDT) |
| Mounting Type | Surface mount (#8 screws) |
| Dimensions | 74.42 x 133.86 x 74.93 mm (2.93 x 5.27 x 2.95 in), H x W x D |
| Operating Temperature (Storage) | -40...+70 °C (-40...+80 °C) |
| Approvals | UL 508 |