ALSTOM MVAJ105RA0802A Protection Relay
Product Overview
The MVAJ105RA0802A is an electromechanical protection relay of the GE ALSTOM MVAJ 05/10/20‑series AC/DC trip‑control type. It is a 10‑contact model featuring dual reset via manual and electrical means. Housed in a standard Midos Size 2 enclosure, it is designed for secondary‑protection circuits in substations. Its core function is to receive weak‑current signals from protection devices, amplify contact capacity to directly drive circuit‑breaker trip coils, and provide multiple auxiliary contacts for interlocking, alarm signalling and remote‑reset logic configuration.The MVAJ105RA0802A comes in a high‑load configuration; a low‑load mode can be selected using terminal short‑circuit links. It offers strong immunity against interference from cable capacitive discharge. Widely used in complete protection systems for main transformers and high‑/low‑voltage switchgear, the unit delivers extremely fast operation through a hinged‑armature mechanical structure to ensure reliable circuit‑breaker tripping during grid short‑circuit and earth‑fault conditions. Following the discontinuation of the older ALSTOM MVAJ11‑34 series, the MVAJ105RA0802A is one of the primary replacement models, enjoying large installed‑base volumes and high application coverage across projects.
Technical Specifications
(I) Model Breakdown (MVAJ105RA0802A)
- MVAJ：Series designation, trip‑and‑control relay
- 10：10‑contact output per unit
- 5：Manual + electrical dual‑reset mechanism
- R：Midos Size 2 enclosure (compatible with 10‑contact / 5‑contact variants)
- A：Standard manual fault flag (standard for trip relays)
- 08：Rated control voltage 110/125 V DC
- 02：Contact combination code: 6 normally‑open, 4 normally‑closed
- A：Design suffix for standard configuration
(II) Electrical Performance Parameters
- Operating time：＜8 ms under standard‑flag condition; contact bounce increment ≤1 ms; 15 ms for switch‑follow flag‑control mode
- Reset time：Electrical reset ＜15 ms
Load Power Consumption
- High‑load mode: Operating power 50~150 W, holding power 4 W, reset power ＜40 W
- Low‑load mode: Instant power reduction after removing the short‑link across terminals 22 and 24
Capacitive‑discharge withstand capability (high‑load, 110/125 V range)
- 10 μF capacitor charged to 120 % rated voltage, no false operation upon discharge; low‑load mode withstands only 1 μF capacitive discharge
Contact Ratings
- Short‑time make‑and‑break (3 s): AC 7500 VA (30 A / 300 V), DC 7500 W (30 A / 300 V)
- Continuous carry: AC 1250 VA (5 A / 300 V), DC 1250 VA (5 A / 300 V)
- Breaking capacity: AC 1250 VA; DC resistive 80 W, DC inductive 40 W (L/R = 0.04 s), max. 5 A / 300 V
- Operating voltage range (code 08: 110/125 V): 66 V ~ 150 V DC
- Mechanical‑electrical endurance: Minimum 10 000 operations for loaded contacts; minimum 100 000 operations for unloaded contacts
(III) Mechanical Dimensions (Midos Size 2 Enclosure)
- Overall height: 177 mm
- Panel cut‑out: 48 mm width × 159 mm height
- Mounting holes: 4 × Φ4.4 mm
- Maximum button protrusion: 10 mm
- Embedded mounting depth: 212 mm
- Minimum rear clearance for heat dissipation: 25 mm
Core Functional Advantages
- Dual‑reset compatible designThe MVAJ105RA0802A integrates local manual push‑button reset and remote electrical‑coil reset, covering both on‑site lockout and remote‑reset maintenance scenarios. Reset‑inhibit terminal function is available to prevent relay oscillation caused by simultaneous energization of trip and reset circuits.
- One‑switch high‑/low‑load selectionFactory‑wired high‑load setting suits long‑distance trip cables and prevents false tripping induced by cable capacitive discharge during earth faults. Remove the 22‑24 terminal short‑link to activate low‑load mode for control cabinets where protection devices are installed in close proximity.
- Multi‑contact expansion capability10 independent contacts (6NO + 4NC) per unit. Multiple‑circuit‑breaker tripping, fault annunciator lamps, remote‑station alarms and electrical interlock loops can be driven simultaneously without auxiliary relays, simplifying secondary‑wiring work.
- Delay cut‑off protectionUnder high‑load condition, a 40‑60 ms power‑delay cut‑off function ensures series‑connected MCAA repeating relays and signal indicators complete full actuation before coil power consumption drops, improving overall protection‑logic reliability.
- Visual fault‑indicating flagEquipped with manual‑reset fault flag. The flag pops out and latches after operation, allowing maintenance personnel to quickly identify tripped circuits and distinguish transient faults from permanent lock‑out faults.
- Minimized contact bounceHinged‑armature mechanical structure suppresses contact chattering, mitigating secondary‑circuit harmonic and pulse interference, and extending service life of circuit‑breaker trip coils and auxiliary signalling components.
Product Features
- Mechanical Construction: The entire series adopts hinged‑armature electromagnetic mechanism. A residual air gap is reserved in the magnetic circuit to guarantee reliable return for self‑reset variants. The dual‑reset MVAJ105RA0802A is fitted with an independent latching structure to maintain stable operated status after fault tripping.
- Power Supply Compatibility: Low‑load mode supports both AC and DC operation; high‑load mode operates on DC only. The MVAJ105RA0802A is rated for 110/125 V DC, matching the majority of DC operating‑power standards for domestic substations.
- Protection Logic: Reset‑inhibit function is activated by short‑circuiting terminals 21 and 23. The reset circuit is automatically blocked while the operating coil is energized, preventing relay oscillation and internal‑contact burnout.
- Time‑delay Characteristics: 2.5 s automatic‑reset timing is not available (this function is exclusive to MVAJ102/202 models). The cut‑off delay of MVAJ105RA0802A is fixed at 40‑60 ms.
- Mounting Method: Standard flush panel‑mounting with industrial‑standard Midos enclosure. Units of identical size can be densely arranged side‑by‑side within cabinets and fit standard relay‑protection panel cut‑out dimensions.
- Environmental Adaptability: Tolerates heavy electromagnetic interference in substation environments and complies with industry standard ESI 48‑4 EB1/EB2. Wide voltage‑tolerance range accommodates float‑charge and discharge voltage variations of DC battery banks.
Application Fields
- Complete‑set protection for power main transformers: Used together with gas relays, differential protection and zero‑sequence protection to implement interlocked tripping of high‑ and low‑voltage‑side circuit breakers. Manual latching after faults prevents false closing by auto‑reclosing devices.
- Relay circuits for high‑voltage switchgear: Serves as output intermediate trip relay for protection devices, providing multi‑contact expansion for circuit‑breaker trip coils, fault alarms and remote measurement‑control signalling.
- Auto‑reclosing supporting logic: Electrical‑reset function enables remote relay‑status reset upon completion of reclosing cycles, suitable for sectional‑protection systems on overhead transmission lines.
- Distributed long‑distance tripping circuits: High‑load mode applies to remote circuit‑breakers with cable lengths exceeding 50 m, suppressing false tripping triggered by distributed‑capacitance discharge of cables.
- Industrial‑plant and captive power plants: Output‑contact expansion for generator‑unit differential and stator‑earth‑fault protection, implementing interlocked tripping of generator main breakers and auxiliary‑power switches.
- Railway traction substations: Secondary interlocking for DC‑feeder protection and centralized uploading of fault‑alarm signals.
Product Comparison
MVAJ101RA: Auto‑reset type with 10 contacts, no latch. It automatically resets upon disappearance of fault signals and is suitable for basic reclosing circuits. Compared with MVAJ105RA0802A, it has no manual blocking function and cannot be applied to main transformer primary protection.
MVAJ102RA: 2.5 s delayed auto‑reset with automatic‑only reset function, used for time‑delayed inter‑tripping between high‑voltage and low‑voltage circuit breakers. MVAJ105RA0802A has no delay and features permanent‑fault blocking.
MVAJ103RA: Pure manual single‑reset; reset is performed only via front‑panel push‑button, without remote electrical reset. MVAJ105RA0802A supports both local and remote dual reset for superior operation‑maintenance flexibility.
MVAJ104RA: Pure electrical single‑reset; no manual push‑button, reset is achieved only remotely. MVAJ105RA0802A is compatible with both reset modes to fit full‑scenario operation and maintenance.
MVAJ105RA0802A: Dual reset (manual + electrical). Faults can be blocked locally and reset remotely. Equipped with 10 expandable contacts, it is the preferred model for main‑transformer and high‑voltage cabinet protection applications.
Supporting Products
(1) Trip‑circuit Monitoring Accessories
MVAX11: Trip‑circuit supervision relay. Connected in series with MVAJ105RA0802A to monitor trip‑cable wire breakage and coil burnout, applicable to high‑load long‑distance circuits.
MVAX31: Full‑condition circuit‑breaker trip‑supply supervision relay. It acquires auxiliary‑contact signals from MVAJ105RA0802A to upload power‑supply abnormality alarms.
(2) Series Delay / Repeat Relays
MCAA: Repeat auxiliary relay. Connected in series on the output circuit of MVAJ105RA0802A, it enables synchronous triggering of multiple signal groups within a 40‑60 ms delay window.
(3) Cabinet Test Accessories
MMLB: 4 mm stacked safety test plug. Used for secondary‑circuit injection tests with MVAJ105RA0802A, providing finger‑safe insulation protection.
MMLG: Standard relay‑protection test base, compatible with plug‑in calibration for MVAJ105RA0802A in Midos2 housings.
(4) Upstream Protection Devices
ALSTOM P632: Transformer differential‑protection device. Its output signals are fed into the expanded trip contacts of MVAJ105RA0802A.
GE N60: Line‑protection relay. Deployed together with MVAJ105RA0802A to build distributed tripping systems.
Supply Advantages
Full‑model in‑stock inventory: New complete units of MVAJ105RA0802A are consistently kept in stock. A full range of alternative models for the MVAJ series are also available to address the pain point of discontinued spare parts for legacy MVAJ11‑34 units.
Complete model customization capability: MVAJ105‑series complete units with various voltage codes (00/02/05/08/10) and contact configurations can be customized on demand to match DC power supply specifications of different substations.
Extended warranty period: A 12‑month warranty is provided for complete MVAJ105RA0802A units.
Bulk turn‑key delivery: Associated components including MVAX, MCAA and MMLB can be shipped simultaneously. All components for trip‑protection circuits are supplied in one‑stop, shortening project delivery lead‑time.
FAQ
Q1: What voltage does code 08 stand for in model MVAJ105RA0802A, and which substation power supplies in China is it compatible with?A1: Code 08 corresponds to rated 110/125 V DC with an operating voltage range of 66‑150 V. It can be directly applied to standard DC operating power supplies for domestic 110 kV and 220 kV substations.
Q2: Can MVAJ105RA0802A switch to low‑load mode? What are the limitations after switching?A2: Low‑load mode is activated by removing the external link between terminals 22 and 24. Low‑load mode is only suitable for nearby‑installed protection devices with recommended cable length ≤20 m. Low‑load mode supports both AC and DC operation, while high‑load mode operates on DC only.
Q3: What is the core difference between MVAJ105RA0802A and MVAJ103RA? Which model shall be selected for transformer protection?A3: MVAJ103RA only supports front‑panel manual reset without remote electrical reset. MVAJ105RA0802A features dual manual‑and‑electrical reset. For main‑transformer protection requiring remote reset of latching circuits after faults, MVAJ105RA0802A is the preferred choice.
Q4: What is the function of short‑circuiting reset‑inhibit terminals 21 and 23 of MVAJ105RA0802A? In which scenarios shall this function be enabled?A4: Short‑circuiting terminals 21 and 23 activates reset inhibition, which automatically cuts off the reset circuit when the relay is energized. This function must be enabled under auto‑reclosing logic where trip signal and reset signal may be energized simultaneously, to prevent relay oscillation and damage.
Q5: Can MVAJ105RA0802A directly drive trip coils of two circuit breakers? Are contact ratings sufficient?A5: A single normally‑open contact achieves 30 A short‑time making‑and‑breaking capacity. If the total current of two conventional circuit‑breaker trip coils is below 5 A, parallel direct driving is feasible. For overload conditions, separate outputs via two independent contacts are recommended.
Q6: What are the root causes when the indicator flag fails to pop‑up after MVAJ105RA0802A operates?A6: 1. Insufficient energizing voltage lower than 66 V fails to fully pull‑in the armature. 2. Dust accumulation causes jamming of the flag slot. 3. Wear‑out of internal latching mechanical structure, complete unit replacement is required.
Q7: What is the purpose of the 40‑60 ms time‑delayed cut‑off under high‑load mode for MVAJ105RA0802A?A7: The delay window ensures series‑connected MCAA repeat relays and alarm indicator components complete their operation before coil power consumption is reduced, avoiding incomplete component actuation and subsequent protection logic failure.
Q8: Obsolete ALSTOM MVAJ25 relay is discontinued. Can MVAJ105RA0802A serve as a direct replacement?A8: Yes, direct replacement is feasible. Reset logic, contact ratings and housing mounting dimensions are fully compatible. Only verify matching of control‑voltage code.
Recommended Peer‑brand Models
MVAJ051RA0800A 5‑contact auto‑reset trip relayMVAJ053RA0800A 5‑contact manual‑reset trip relayMVAJ055RA0800A 5‑contact manual‑electrical dual‑reset trip relayMVAJ101RA0800A 10‑contact auto‑reset trip relayMVAJ102RA0800A 10‑contact 2.5 s delayed auto‑reset trip relayMVAJ103RA0800A 10‑contact manual‑reset trip relayMVAJ104RA0800A 10‑contact electrical‑reset trip relayMVAJ105RA0802A 10‑contact manual‑electrical dual‑reset trip relayMVAJ203TA0800A 20‑contact manual‑reset trip relayMVAJ204TA0800A 20‑contact electrical‑reset trip relayMVAJ205TA0800A 20‑contact manual‑electrical dual‑reset trip relay
3005319639