The MVAJ23B1AB0757B of GEC ALSTHOM is a very classic High load, High Speed Tripping Relay.

It belongs to the Midos series protection system and is mainly used in power systems such as substations and power plants to execute the final circuit breaker trip command.

In-depth Analysis of the Meaning of model codes

MVAJ 23: This sub-series is specially designed as “locking type” relays. Once the trigger signal is triggered and the action is taken, the contact will mechanically lock at the trigger position.

B: Contact configuration code, representing 10 pairs of contacts.

Contact type code, referring to standard contacts.

A: The shell Size corresponds to a case with a width of Size 2.

B: Auxiliary voltage rating, referring to 110/125V DC. This is the most crucial parameter of this relay. It is strictly forbidden to connect alternating current or direct current of different grades incorrectly.

0757B: This is a specific manufacturing specification code (which may contain specific wiring logic or factory calibration standards).

3. Main Functions and Advantages

High Burden characteristic: Complies with the ESI 48-4 EB2 standard of the United Kingdom.

This means that it has extremely strong anti-interference ability against distributed capacitance discharge generated by long-distance cables.

In simple terms, it will not trip due to induced electricity in the line or momentary noise, and its safety is extremely high.

Mechanical Flag: The relay panel is equipped with a prominent red mechanical indicator. When the tripping action occurred, the red flag fell.

Even if the DC power supply is lost, the red flag will remain until it is manually restored.

Double return

MVAJ23B1AB0757B

Manual reset: The operator must go to the site and press the reset button below the relay.

Electrical reset: A pulse signal can be remotely sent to the reset coil from the central control room for reset.

4. Typical wiring reference (based on MVAJ23)

Although the specific terminals need to be referred to the wiring diagram on the side of the relay, the standard configuration is usually as follows:

Action circuit: Trigger signal input, usually connected to terminals 27(+) and 28(-).

Reset loop: Remote reset signal input, usually connected to terminals 25(+) and 26(-).

Output contacts: 10 groups of independent contacts are distributed between terminals 1 and 20