ALSTOM MVAX91W1DD0754A

Technical Core Specifications

• Integrated Channel Count: Three fully independent trip circuit supervision channels in single chassis housing
• Supervision Coverage: Monitors trip circuit integrity whether circuit breaker contact is open or closed
• Fault Detection Types: Trip coil open circuit, broken control wiring, trip DC supply loss, seized breaker trip mechanical mechanism
• Alarm Output: Potential-free changeover contact sets for remote SCADA fault signaling and local panel alarm lamp drive
• Operating Supply: Standard substation DC control voltage (suffix 0754A defines coil voltage specification)
• Mechanical Construction: Attracted armature relay design with chatter-free positive mechanical contact switching
• Chassis Form Factor: 40TE Eurocard rack mount unit compatible with Alstom substation protection panel backplanes
• Environmental Protection Grade: IP5X dust-proof sealed internal mechanism
• Operating Temperature Range: -25°C ~ +70°C continuous substation environment operation
• Anti-Vibration Standard: Compliant with IEC 60255-21 power substation relay vibration testing

Functional Features

1. Three independent fully isolated trip circuit monitoring channels support simultaneous supervision of three separate circuit breaker trip loops within one compact unit
2. Continuous supervision operates regardless of circuit breaker open/closed mechanical state for uninterrupted fault detection
3. No false alarm triggering from momentary trip coil energization during normal circuit breaker switching operations
4. Visual front-panel fault indication LED per individual monitoring channel for rapid local fault location identification
5. Potential-free alarm contacts allow connection to remote SCADA telemetry systems for central grid control room fault notification
6. Chatter-free attracted armature mechanical design eliminates contact bounce under substation vibration conditions
7. Plug-in modular chassis enables single-unit replacement without full panel power isolation during maintenance
8. Immunity to long trip wiring cable capacitive leakage current preventing spurious fault alarm activation

Material & Structural Composition

• Main Chassis Frame: Welded steel alloy Eurocard rack frame with epoxy anti-rust coating
• Internal Relay Sub-units: Silicon steel electromagnetic armature assemblies with copper wound monitoring coils
• Contact Mechanisms: Silver alloy anti-arcing SPDT contact sets mounted on spring copper leaf arms
• Front Indicator Panel: Transparent polycarbonate viewing window with channel labeled fault LED indicators
• Terminal Socket Base: Multi-way nickel-plated screw terminal plug base for field trip wiring connection
• Anti-Vibration Components: High-density rubber elastomer shock isolation pads between internal sub-units and chassis frame

Working Principle

Installation Requirements

1. Install within sealed IP44 minimum rated substation control panels to prevent dust and moisture contamination of internal relay mechanisms
2. Separate trip supervision wiring from high-voltage AC power cabling with minimum 10cm physical clearance to reduce electromagnetic interference
3. All field trip circuit wiring must use 1.5–2.5mm² shielded twisted copper control cable with single-point cabinet earth bonding
4. Torque terminal wiring screws to factory specified 3.5 Nm tension to avoid high-resistance loose connection false fault triggers
5. Maintain minimum 25mm vertical air gap above and below the MVAX91 chassis for passive heat dissipation
6. Mount chassis in strictly vertical orientation; horizontal installation invalidates vibration resistance performance specifications

Application Scenarios

Operation & Maintenance Notes

1. Conduct quarterly functional test of all three supervision channels by manually breaking trip loop wiring to verify fault alarm response
2. Wipe front indicator window surfaces monthly to remove accumulated dust blocking fault LED visibility
3. Avoid installation in coastal salt-spray or chemical plant corrosive vapor environments without fully sealed panel enclosures
4. Check terminal block wiring tightness bi-annually to eliminate resistance drift triggering false trip circuit fault alarms
5. Replace entire MVAX91 unit if individual internal supervision channel sub-units suffer mechanical contact failure
6. Maintain spare inventory of identical model relays to enable immediate hot-swap replacement during critical grid operation periods