ALSTOM MVAJ105RA0802A High-speed Trip Lockout Relay Detailed Explanation
I. Product Positioning
MVAJ105RA0802A belongs to the MVAJ series of articulated armature-type high-speed trip relays (Trip Relay), originally an Alstom (subsequently merged into GE Grid Solutions) product. It is widely used in substation / power plant relay protection panels, receiving trip instructions from protection devices and directly driving the circuit breaker’s trip coil to achieve rapid fault tripping + fault action locking, preventing automatic reclosure at the fault point after a fault.
Model Code Decomposition
MVAJ: Product series = High-speed Trip and Control Relay
105: Basic specification code, 10 contacts (6 normally open + 4 normally closed as the main type)
R: Equipped with manual reset + electrical reset dual reset methods, after operation, the mechanism remains locked in the closed state, and must be manually / by electrical signal reset to release the lock.
A: Coil power supply mode (DC operation)
08: Coil rated working voltage 80V DC (commonly used level for power plant protection DC operating power supply)
02A: Internal wiring / contact layout version number
Core Performance Characteristics
Extremely fast action speed
Typical action time < 10ms, for short-circuit faults, it can quickly issue a tripping command, reducing equipment short-circuit damage.
Contact anti-jitter design
The mechanism is optimized to almost eliminate contact bouncing, avoiding intermittent tripping signals, coil burnout, and auxiliary signal false alarms.
Load switching (Burden) capability
Built-in external jumper can switch between high and low load modes; in the high-load mode, it can resist cable capacitance discharge interference, and when long-distance DC cable wiring is used, it will not cause false tripping due to line distributed capacitance discharge, which is very suitable for high-voltage substations with long secondary cables scenarios.
Trip lockout + trip indication flag
After the relay trips, it is mechanically locked, and the panel shows the action indicator, allowing maintenance personnel to directly see which protection output has tripped; if not reset, it will remain in the tripped state, preventing the faulty equipment from being re-energized.
Strong load-bearing capacity
The contacts can directly drive the circuit breaker’s trip coil, such as in heavy-load heavy-duty loads, without the need for additional intermediate relays for connection, simplifying the secondary circuit.
Key Electrical & Structural Parameters
Operating voltage: 80VDC
Contact quantity: 10 points (6NO + 4NC), capable of simultaneously outputting trip, alarm, remote transmission signals, and multi-device interlock
Reset method: Local manual mechanical reset + remote electrical reset
Installation method: Plug-in frame / panel rail installation, with transparent dust-proof cover
Anti-interference characteristics: Suppressing false tripping caused by secondary cable distributed capacitance discharge
Applicable standards: IEC 60255 Relay Protection Standard
Typical Application Scenarios (Combined with Your Previous Equipment)
Generator / Transformer Protection Export Trip: After the main protection action, drive this relay, then disconnect the circuit breaker;
Steam Turbine Protection Interlock: Woodward 505XT (8200-1312) overspeed protection export is linked to this trip relay, cutting the main steam valve and tripping the generator switch;
Vibration Protection Interlock: Bently 3500 shaft vibration over-limit signal is connected, and it is executed through MVAJ to perform hard circuit trip;
Trip status signal can be connected to ControlLogix PLC, and then uploaded to the intelligent substation IEC61850 monitoring system, sending the trip event SOE record.
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