3-Phase Monitors

Description

The Model 257 continuously monitors 3-phase power lines for abnormal conditions. When properly adjusted, the Model 257 monitor will detect phase loss on a loaded motor even when regenerated voltage is present.

This device consists of a solid-state voltage and phase-angle sensing circuit, driving an electromechanical relay. When correct voltage and phase rotation are applied, the internal relay will energize. A fault condition will de-energize the relay. When the fault is corrected, the monitor will automatically reset (a manual reset version is also available).

The Model 257 does not require a neutral connection and can be used with Wye or Delta systems. Voltage ranges are sufficiently wide to allow for proper adjustment to existing conditions. Both TRIP and NORM condition indicators are provided to aid in adjustment and system trouble-shooting.-

Specs

AUTO Reset
MANUAL Reset

B258B
B258BM

258B
258BM

A258B
A258BM

EX258B
EX258BM

B258B-400
B258BM-400

258B-400
258BM-400

Nominal AC Voltage
(phase to phase)

120VAC 

208/240VAC 

480VAC 

380VAC 

120VAC 

208/240VAC 

Case Color

 Gray

Red 

Yellow 

Yellow 

Gray 

Red 

Adjustment Range

 85-120VAC

160-240VAC 

380-480VAC 

300-400VAC 

85-120VAC 

160-240VAC 

Frequency

 60 Hz

60 Hz 

60 Hz 

50 Hz 

400 Hz 

400 Hz 

Power Consumption

0.75W 

1.5W 

4.5W 

3.75W 

 0.75W

1.5W 

1 User Review

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Anonymous
We are facing a problem of voltage drop during the night time. Our factory is getting supply from state electricity board.Our machine are very sensitive to even small drop in supply voltage. So we would like to automatically monitor the supply voltage. Please suggest us a good device.
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