SKU: MMLG02R1AA0001E

ALSTOM MMLG02R1AA0001E MMLG Series Relay Test Block

The ALSTOM MMLG02R1AA0001E is a 14-circuit relay test block featuring CT shorting protection and 20A current capacity. Designed for M-series protection schemes, it enables safe and rapid secondary injection testing without disconnecting permanent field wiring in high-voltage substations.

Primary System Role

The ALSTOM MMLG02R1AA0001E operates as a specialized safety interface within protection relay panels and electrical switchgear. Specifically, this test block allows technicians to perform essential secondary injection tests and maintenance without disconnecting the primary field wiring. By inserting a compatible test plug, the unit automatically shorts current transformer (CT) circuits and opens voltage circuits to isolate the relay from the rest of the system. Because it eliminates the need to disturb permanent connections, the MMLG02R1AA0001E significantly reduces the risk of open-circuit CTs, which could otherwise cause catastrophic high-voltage surges during testing.

Enhanced Technical Performance

Ensures Personnel Safety: The module utilizes a “make-before-break” contact sequence on CT circuits. In doing so, it guarantees that the current path remains closed at all times, thereby preventing dangerous electrical arcing during test plug insertion.
Simplifies Maintenance Procedures: The test block groups up to 14 individual circuits into a single compact housing. As a result, maintenance teams can access multiple protection loops simultaneously from the front of the panel, effectively shortening the duration of periodic relay inspections.
Protects Sensitive Logic: The unit features a robust isolation barrier between adjacent contacts. Consequently, it prevents accidental cross-conduction between protection channels, ensuring that testing one relay does not cause a nuisance trip in another.
Facilitates Rapid Diagnostics: Beyond standard testing, the MMLG02R1AA0001E allows for easy measurement of current and voltage levels using standard probes. Therefore, technicians can verify secondary circuit values in real-time while the primary system remains energized.
Maintains Long-Term Reliability: Finally, the module employs high-quality silver-plated contacts and a durable poly-carbonate cover. By resisting oxidation and dust ingress, the unit maintains low contact resistance over decades of service in utility substations and industrial plants.

Technical Specifications

Model Identifier: MMLG02R1AA0001E
Product Series: MMLG (M-Series)
Configuration: 14 Independent Circuits
Contact Type: Shorting (for CT) and Non-shorting (for VT/Trip)
Maximum Current Rating: 20 A (Continuous)
Maximum Voltage Rating: 300 V AC / DC
Mounting Type: Flush Panel Mount (4U Height)
Insulation Resistance: > 100 MΩ at 500 V DC
Standard Compatibility: IEC 60255 (Measuring relays and protection equipment)
Dielectric Strength: 2 kV RMS for 1 minute
Housing Material: Flame-retardant thermoplastic