257B Series Elevator Power Monitors - Phase-Fault & Voltage Protection (85–480 VAC)
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257B Series Elevator Power Monitors - Phase-Fault & Voltage Protection (85–480 VAC)
257B Series | Elevator Power Monitors
The 257B Series power monitors continuously track three-phase power lines to detect phase loss, phase reversal, and under-/over-voltage conditions across 85–480 VAC. Available in both automatic-reset (Bxxx) and manual-reset (BM) designs, they offer tailored fault-recovery strategies for elevator traction, control, and auxiliary circuits.
Featuring wide adjustment ranges, SPDT relay outputs rated 10 A @ 240 VAC, and compact ABS housings that mount on standard 8-pin sockets, these monitors deliver dependable phase-fault protection backed by a five-year warranty.
- Automatic-reset (Bxxx) and manual-reset (BM) relay options
- Monitors phase loss, phase reversal, and under-/over-voltage conditions
- Adjustable voltage ranges: 85–120 VAC, 208/240 VAC, 380–480 VAC
- Compatible with Wye and Delta systems; no neutral required
- SPDT relay output rated 10 A @ 240 VAC resistive
- Compact ABS plastic housing; mounts on 8-pin socket (sold separately)
- 5-year unconditional warranty
View Monitor Specifications
| Model | Nominal Voltage | Frequency | Application |
|---|---|---|---|
| B257B | 85–120 VAC | 60 Hz | Low-voltage control circuits and auxiliary power monitoring |
| B257BM | 85–120 VAC | 60 Hz | Manual-reset monitor for low-voltage systems requiring fault verification |
| 257B | 208/240 VAC | 60 Hz | General-purpose elevator power monitoring and phase-fault protection |
| 257BM | 208/240 VAC | 60 Hz | Manual-reset monitor for control circuits requiring maintenance checks |
| A257B | 380–480 VAC | 60 Hz | High-voltage traction system monitoring and fault detection |
The 257B Series delivers robust, code-compliant phase-fault protection for elevator systems. Always confirm the correct reset type and voltage rating before installation.
