Beckwith M‑0388 Syncrocloser Check Relay

The Beckwith M‑0388 is a syncrocloser check relay designed to ensure that synchronism conditions are met before a circuit breaker is closed. It monitors the voltage difference, phase angle, and slip frequency between two AC sources and provides a permissive signal only when all parameters are within predetermined limits. This relay is essential for generator paralleling, bus transfer, and network interconnection applications.

The M‑0388 features high‑precision measurement circuits and adjustable setpoints, allowing it to be tailored to specific system requirements. Its compact housing and clear status indicators facilitate easy installation and operation.

Key Features

• Adjustable phase angle window: ±5° to ±20°

• Voltage matching: 80–120% of nominal

• Slip frequency detection: 0.05–2.0 Hz

• Dead‑bus and live‑bus closure logic

• Output relay for close permissive

• LED indicators for match and fail status

• Wide operating temperature range

Technical Specifications

Inputs: 120/240 VAC, 50/60 Hz; burden: < 5 VA; accuracy: ±0.5% voltage, ±0.02 Hz; output: 1 x SPDT, 5 A; operating temperature: -20°C to +65°C; enclosure: panel mount.

Applications

Used in generator synchronizing panels, automatic transfer switches, and tie‑breaker control schemes. Ensures safe closing of breakers without mechanical or electrical stress.

Installation and Setting

Mount the relay on a panel. Connect voltage leads from both sides of the breaker. Adjust the phase angle, voltage, and frequency windows via the front‑panel controls. A built‑in test function aids commissioning.

Reliability and Maintenance

Solid‑state design provides high reliability and immunity to vibration. Regular verification of setpoints is recommended.

Why Choose the M‑0388?

This relay offers a reliable and cost‑effective solution for sync‑check applications, with Beckwith Electric’s proven quality ensuring consistent performance.

In summary, the Beckwith M‑0388 enhances the safety and reliability of power switching operations by confirming synchronism before closure.