Description

The ALSTOM / GE Vernova MVAJ101RA0800A is a high-speed, multi-contact hinged armature auxiliary trip relay designed for critical tripping and interlocking applications within power substations, generating plants, and industrial distribution systems. Part of the well-established Midos range (Size 2 enclosure), this electromechanical relay provides high-reliability buffering between protective monitoring devices and heavy-burden circuit breaker trip coils. It features rapid contact closure, high thermal capacity, and a robust mechanical latching system to guarantee positive breaker operation during electrical fault conditions.

Commercial and Lifecycle Logistics

+---------------------------+------------------------------------------------------------+
| Parameter                 | Value                                                      |
+---------------------------+------------------------------------------------------------+
| Product Condition         | New Original (Factory Sealed Surplus or Tested Refurbished)|
| Warranty                  | 12-Month Comprehensive Warranty                            |
| Availability              | In Stock / Ready for Worldwide Export                      |
| Standard Lead Time        | 1–3 Business Days via DHL Express / FedEx / UPS            |
| Price Notice              | Price subject to market conditions; contact us for a firm  |
|                           | quote                                                      |
+---------------------------+------------------------------------------------------------+ 

Hardware Architecture and Technical Specifications

The specific model code MVAJ101RA0800A indicates a distinct configuration regarding contact count, resetting mechanics, and auxiliary operating voltage.

Contact Arrangement and Reset Characteristics

• Contact Configuration: 10 contacts total, typically ordered as 10 Normally Open (10 NO) or a split combination such as 8 Normally Open and 2 Normally Closed (8 NO / 2 NC).
• Reset Type: Hand Reset Only. When an electrical fault triggers the internal armature, the relay latches mechanically and drops a high-visibility physical target flag. The relay and the flag can only be reset by physically pressing the mechanical reset lever on the front cover of the Midos case.

Electrical and Performance Metrics

• Auxiliary Rated Voltage (V_x): 110 V to 125 V DC rating.
• Operating Speed: \le 10 ms at nominal rated V_x, facilitating high-speed fault isolation to minimize upstream system stress.
• Contact Rating: Continuous thermal current rating of 10 A. Short-time withstand current rating of 30 A for 3 seconds.
• Contact Bounce: Controlled to < 2 ms via specialized contact geometry and high mechanical tension armatures.

Burden and Noise Immunity

• High Burden Architecture: Configured to draw a high instantaneous current spike upon initiation to overcome line capacitance and electrical noise induced on long battery-room cable runs. This protects against accidental trips caused by DC battery earth faults.
• Economizing Circuit: An internal mechanical cut-off switch safely interrupts the high initiation current within 40 ms of positive armature latching, reducing the steady-state holding burden to negligible levels.

Application and Installation Guidelines

Critical Engineering Insight:

The MVAJ101 model variant is entirely mechanical-latched and lacks an electrical reset coil. It is specifically designed for local-control or manned-substation panels where an operator must physically inspect the protection panel and clear the flag manually before the associated circuit breaker can be safely reclosed.

• Wiring Precautions: Because this relay operates as a high-burden device upon initial pickup, confirm that the upstream protective relay contacts (e.g., differential, distance, or overcurrent relays) have sufficient making and breaking capacity to handle the peak initialization current.
• Draw-Out Maintenance: The Midos case incorporates automatic shorting actions for current transformer (CT) loops if applicable, but standard practice dictates isolating the DC battery supply fuses before extracting the internal MVAJ relay module from its outer housing.
• Mounting Alignment: To maintain precise mechanical latching thresholds and drop-flag visibility, mount the enclosure on a vertical panel plane.

Frequently Asked Questions (FAQ)

What is the fundamental difference between the MVAJ101 and the MVAJ105?

The MVAJ101 relies exclusively on Hand (Manual) Reset to restore the contacts and target flag to their nominal state. The MVAJ105 features a dual mechanism providing both Hand and Electrical Reset, which includes an internal remote reset coil allowing operators to clear the latched state from a remote SCADA HMI or RTU link.

Can the MVAJ101RA0800A operate on an AC auxiliary control voltage?

No. The MVAJ101 high-burden variant with this specific configuration code is designed for DC control circuits. Applying an AC control voltage to the initialization terminals can cause severe contact chattering, failure to latch fully, and permanent thermal damage to the internal economizing circuits.

What parameters should be verified prior to replacing an older Alstom MVAJ relay?

Confirm the precise model suffix. Variations in the code dictate whether the unit is high or low burden, the exact contact layout split (NO vs NC combinations), and the factory voltage rating. Check the original terminal schematic diagram against the side-label schematic on the replacement unit before inserting the chassis into the existing Midos housing.