Model B258BM-400 3-Phase Monitor

B257BM-120VAC

The Model B258BM-400 3-Phase Monitor provides critical oversight for industrial electrical systems. Designed for 120VAC nominal applications, it offers an adjustable monitoring range of 85-120VAC, ensuring precise voltage control. This monitor actively detects detrimental conditions including phase loss, low voltage, and phase reversal, thereby preventing potential equipment damage and operational downtime. Operating at 400Hz, its 50ms drop out response time facilitates rapid system protection. The unit features durable SPDT 10 amp output contacts, capable of managing significant loads. Its operational integrity is maintained across a wide temperature spectrum, from -20° to +131° F, and it tolerates 0-97% humidity without condensation. This robust construction, coupled with a five-year unconditional warranty, ensures sustained performance and reliability in demanding environments.

3Ph Pm Mnl Reset

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b257bm-120vac

Specifications

Reset TypeMANUAL Reset
Nominal AC voltage (phase to phase)120VAC
Case ColorGray
Adjustment range85-120VAC
Frequency400Hz
Power consumption1.4W
Protection FeatureDetects phase loss, low voltage, phase reversal
WarrantyFive year unconditional warranty
Transient protection2500VAC for 10ms
Repeat accuracy± 0.1% of set point (fixed conditions)
Response time50ms drop out
Dead bandApprox. 2%
Output contactsSPDT 10 amps at 240VAC resistive
Expected relay life (Mechanical)10 million operations
Expected relay life (Electrical)100,000 operations at rated load
Operating temperature-20° to +131° F
Humidity tolerance0-97% w/o condensation
Enclosure materialABS plastic cover
Mounting8-pin socket (**sold separately)
Agency approvalsUL Recognized* and CSA Certified

FAQs

What nominal AC voltage does the B258BM-400 monitor?
The B258BM-400 monitors a nominal AC voltage of 120VAC (phase to phase), with an adjustment range from 85-120VAC.
What types of electrical faults does this 3-phase monitor detect?
This monitor detects phase loss, low voltage, and phase reversal to protect connected equipment.
What are the environmental operating limits for the B258BM-400?
It operates within a temperature range of -20° to +131° F and tolerates 0-97% humidity without condensation.