GE MVAJ Trip Relay: Protection and Control Core

GE MVAJ Trip Relay: Protection and Control Core

MVAJ 05/10/20 Series Trip and Control Relays: Providing Reliable Execution Interface for Power System Protection

In the protection architecture of power systems, protective relays (such as overcurrent, differential, distance protection, etc.) are precision measuring devices, and their contacts usually do not have the large capacity required to directly operate circuit breaker trip coils. Meanwhile, complex protection schemes may require the simultaneous tripping of multiple circuit breakers or the implementation of control functions such as signaling and interlocking. To address this core issue, GE Vernova has launched the MVAJ 05/10/20 series of trip and control relays. This series is based on mature rotary armature technology and aims to provide a highly reliable, flexible, and fast execution interface between protective relays and circuit breakers.

Product Overview: Strong Support for Protection Systems

The MVAJ series relay is essentially an auxiliary relay, but its design goals are far from comparable to ordinary intermediate relays. It is specifically designed for direct operation of circuit breaker trip coils and has the following core values:

High contact capacity: It can safely connect and disconnect large inductive loads such as circuit breaker trip coils, with a contact capacity of up to 7500 VA/W (3 seconds), far exceeding the output capacity of ordinary protective relays.

Multi contact configuration: Provides models with up to 20 contacts, capable of simultaneously tripping multiple circuit breakers, issuing multiple signals, or implementing complex interlocking logic.

High speed action: The tripping type relay has an action time of less than 8-10ms (depending on the model) to ensure that the fault can be quickly isolated.

High reliability: Adopting a sturdy rotating armature design, it has extremely high mechanical stability and electrical life.

Strong anti-interference ability: The specially designed high load configuration gives it natural immunity to the discharge current of the DC system's ground capacitor, making it very suitable for distributed trip circuits.

Model selection and application scenarios

The MVAJ series offers a wide range of model choices based on the number of contacts and reset methods to meet different application requirements.

1. Classify by the number of contacts

Model Series Contact Quantity Shell Size Typical Applications

MVAJ 05 5 contacts Midos Size 2 small switchgear, single circuit breaker control

MVAJ 10 contacts Midos Size 2 standard line protection, transformer protection

MVAJ 20 contacts Midos Size 4 complex busbar protection, multiple circuit breaker tripping

2. Classify by reset method

The MVAJ series provides multiple reset mechanisms to meet different control logic requirements:

Reset type, applicable models, characteristics and applications

The self resetting MVAJ 051, 101, 102 will automatically reset the relay when the start signal disappears. Suitable for line protection and general signal indication that require automatic reclosing. MVAJ 102 is a special model with a 2.5-second delay self reset.

After the MVAJ 053, 103, 203 relay is manually reset and mechanically held, it must be manually reset through the buttons on the panel. Suitable for anti bounce relays that require fault memory, non electric protection of transformers, etc., used as a lockout relay.

Electric reset MVAJ 054, 104, 204 requires an independent reset voltage to be applied in order to reset. Suitable for remote reset or automation system control.

Manual/Electric Reset MVAJ 055, 105, 205 offer both manual and electric reset modes, providing maximum operational flexibility.

Deep analysis of core technical characteristics

1. High load configuration and capacitor discharge tolerance

This is one of the most prominent technological advantages of the MVAJ series. In DC control circuits, long cables have distributed capacitance to ground. When a grounding fault occurs, the energy stored in the capacitor will instantly discharge to the relay coil, which may cause low load relays to malfunction.

High load configuration (factory default): MVAJ relays are set to high load mode at the factory. In this mode, the relay has a higher minimum operating current, allowing it to withstand discharge surges from a 10 μ F capacitor charging to 120% rated voltage (for ≤ 125V specifications) or 100% rated voltage (for 220/250V specifications) without misoperation. This makes it particularly suitable for distributed trip circuits or situations where protective contacts are far away from the relay body.

Low load configuration: The relay can be switched to low load mode by removing the external connector between terminals 22 and 24. At this time, the relay is more sensitive to the starting current and is suitable for local control scenarios where the starting contact is nearby. Its capacitance discharge tolerance is 1 μ F.

2. Load shedding and energy-saving circuit design

In order to reduce power consumption and protect the coil after action, the MVAJ series has designed an intelligent load shedding circuit:

MVAJ 05: Regardless of high or low load configuration, the load is instantly cut off or reduced to energy-saving level after the action.

MVAJ 10/MVAJ 20: In high load configuration, the load will remain at about 40-60ms (with a power consumption of about 100W) after the action, and then be cut off or reduced to energy-saving level. This brief delay ensures that other components connected in series with the relay coil, such as MVAX 11 monitoring relay, MCAA relay, etc., can reliably operate.

3. Action time and contact jitter

For tripping applications, speed is crucial.

Standard trip type (with manual reset flag): The action time of MVAJ 05 and MVAJ 10 is less than 8ms, and MVAJ 20 is less than 10ms.

Control type (with following flag): If the following flag is selected, the action time will increase to about 15ms, so it is generally not recommended for trip circuits with extremely high speed requirements.

Contact shaking: The contact shaking time does not exceed 1ms, ensuring crisp and clean operation and reducing the erosion of the contact by the arc.

4. 2.5-second delay self resetting relay (MVAJ 102)

This is a model specifically designed for specific connected applications. A typical scenario is the mutual tripping of large transformers: when a serious internal fault occurs on the high voltage side, the high voltage side circuit breaker quickly trips, but the low voltage side circuit breaker may be protected and return due to the fault current being cut off, resulting in unreliable tripping of the low voltage side circuit breaker.

After MVAJ 102 is protected (such as gas, differential), its contacts close. Even if the start signal disappears quickly (briefly closes), the timer inside MVAJ 102 starts counting, and the contacts will remain closed for 2.5 seconds, ensuring that the low-voltage side circuit breaker has enough time to complete the trip. If the start signal persists, the relay will remain in action until the signal disappears and then reset with a delay of 2.5 seconds.

User configurable features and external connections

The high flexibility of the MVAJ series is reflected in the ability to change relay characteristics through external connectors without disassembling internal circuits.

1. Load configuration selection

Relay model: High load mode (default), Low load mode (with external connections removed)

MVAJ 051, 053, 054, 055 instantaneous load shedding instantaneous load shedding

MVAJ 101, 103, 104, 105, 203, 204, 205 load shedding after 40-60ms delay instantaneous load shedding

MVAJ 102 is fixed in high load mode-

2. Reset suppression function

For electric reset and manual/electric reset models (MVAJ 104/105/2004/205), the reset suppression function can be enabled by connecting terminals 21 and 23. This function ensures that the reset circuit is electrically locked when the operating circuit is excited, preventing the relay from oscillating (quick action reset action) when both the operating and reset commands are present, thereby protecting the relay and external contacts.

Detailed technical specifications

1. Rated voltage and operating range

Rated voltage (Vx) Operating range (V)

24/27 14.4 – 32.4

30/34 18.0 – 40.8

48/54 28.8 – 64.8

110/125 66 – 150

220/250 132 – 300

2. Power consumption and minimum operating current

Model: Power consumption at maximum rated voltage (W), minimum operating current (mA), minimum reset current (mA)

MVAJ 05 80/150* <40 >25/50*

MVAJ 10 50/150* <40 >25/50*

MVAJ 20 50/150* <80 >25/50*

*Low load/high load configuration

3. Contact capacity

Short time connection and load (3 seconds):

Communication: 7500 VA, maximum value of 30A or 300V

DC: 7500 W, maximum value 30A or 300V

Continuous connection and carrying:

Communication: 1250 VA, maximum 5A or 300V

DC: 1250 W, maximum value 5A or 300V

Breaking ability:

Communication: 1250 VA, maximum 5A or 300V

DC: 80W (resistive)/40W (inductive L/R=0.04s), maximum value 5A or 300V

4. Durability

Load contact: 10000 operations (minimum)

No load contact: 100000 operations (minimum)

5. Reset time

Self resetting relay: MVAJ 051 (low load, and 24-54V high load) MVAJ 101：20ms

2.5 second delay self reset: approximately 2.5 seconds

Electric reset:<15ms

Instructions and Signs

1. Manual reset flag

All MVAJ trip relays come standard with a manual reset flag. When the relay is activated, the flag drops. Even if the auxiliary power supply disappears, the flag remains in the active position, indicating that a trip event has occurred. The reset flag can be manually reset through the reset lever on the panel.

2. Follow the sign

Optional follow-up symbol can be installed, which will reflect the current status of the relay in real time (falling when activated and lifting when reset). Mainly used for controlling functions and facilitating on-site observation of equipment status. But as mentioned earlier, it will increase the action time.

Mechanical Structure and Installation

The MVAJ relay adopts the Midos system standardized chassis, which facilitates installation and wiring on the control panel.

MVAJ 05/MVAJ 10: Adopting a Size 2 casing.

MVAJ 20: Adopting a Size 4 casing.

All wiring is completed through the terminal block at the rear of the housing, and the logical relationship between the internal circuit and external wiring needs to refer to the specific model's wiring diagram (such as the MVAJ 21 typical internal wiring diagram provided in the manual).

Ordering Information and Selection Guide

When ordering MVAJ series relays, in order to ensure obtaining products that meet application requirements, the following information must be clearly stated:

Relay model: refers to the specific reset mode sub models under the MVAJ 05, MVAJ 10, or MVAJ 20 series (such as MVAJ 053, MVAJ 104, etc.).

Rated voltage: Select the correct coil voltage specifications (24/27V, 30/34V, 48/54V, 110/125V, 220/250V dc).

Contact combination: For applications with special contact combination requirements, it is necessary to clarify the contact form (such as how many open and how many closed). The manual provides a table of contact combination codes.

Type of flag: Clarify whether a standard manual reset flag (for tripping) or a follow flag (for control) is required.

Special configuration: The 2.5-second delay function of MVAJ 102 is already built-in and does not require additional specification.