Tag: GEC ALSTHOM

MVAJ13D1GB0780A  High-speed tripping and control relays

The MVAJ range consists of highly reliable hinged armature relays designed to directly operate circuit breaker trip coils.

Built to very high specifications, the MVAJ range provides an extremely flexible and reliable link between the protective relays and the circuit breakers.

Numerous features and configurations for multiple tripping schemes

Equipped with a wide range of features and configurations, the MVAJ range can be applied to all types of tripping schemes.

Operating at high speed with very little contact bounce, this range is available in hand, electrical and self-reset models.

An external link connection enables selection of high or low burdens and a delayed cut-off is available for high-burden applications.

The MVAJ range is also equipped with AC or DC operating functions for low burden configurations and it ensures immunity to any wiring capacitance discharge.

MVAJ13D1GB0780A  High-speed tripping and control relays

MVAJ13D1GB0780A

Protective relays are precise measuring devices, the contacts of which should not be expected to switch large electrical loads.

In some cases, the protective relay can trip a circuit- breaker directly, or according to the coil rating and the number of circuits to be energised.

The MVAJ relay interfaces with the protection to provide: higher contact capacity, additional contacts for tripping multiple circuit-breakers, control functions, signalling and interlocking.

The MVAJ range comprises very reliable hinged armature relays designed to directly operate circuit-breaker trip coils. Built to very high specifications, the MVAJ range provides a highly flexible and reliable link between the protective relays and the circuit-breakers.

MVAJ13D1GB0780A

Models Available

Trip relays

Trip relays possess a standard hand-reset flag and operate within 10 ms.

Table 1 shows the trip relay versions available

Control relays

Control relay variants of each trip relay are available. These relays operate within

approximately 15 ms

All relays configured for high burden applications are suitable for DC operation only

The MCGG52H1CB0753C of GEC ALSTHOM is a high-performance microcomputerized overcurrent and ground fault relay, belonging to the classic MCGG series (usually included in the Midos system).

This series is widely used in industrial power distribution and power system protection, and is renowned for its reliable time-limited (DT) and inverse-time (IDMT) protection characteristics.

Basic parameters and model specifications: Full model name

Product type MCGG52H1CB0753C: Two-phase Overcurrent + Earth Fault Protection Relay (2 Phase Overcurrent + Earth Fault)

Rated current ($I_n$) :

1A (Commonly used in the secondary circuit after the distribution ratio

Auxiliary power supply: 48V – 125V DC (suitable for typical substation DC operating systems)

Frequency: 50/60Hz. Universal measurement features: includes Instantaneous and Time Delayed protection elements

2. Main functional features

MCGG52H1CB0753C

Protection configuration: The MCGG52 model is specifically designed for two-phase overcurrent protection along with an independent ground fault channel.

Multiple time curves: Supports multiple standard inverse-time characteristics (selected by dip switches) :

Standard Inverse (SI)

Very Inverse (VI

Extremely Inverse time limit (EI

Long Time Inverse (LTI)

And three Definite Time ranges.

Adjustment range

Current setting value ($I_s$) :

It is usually between $0.05 \times I_n$and $2.4 \times I_n$, with step-by-step refinement. Time multiplier ($TMS$) : Adjustable from 0.05 to 1.0. with a step of 0.025.

Instantaneous element (Iinst) : It can be set from $1 \times I_s$to $31 \times I_s$, and is used for rapid tripping in severe short-circuit faults

3. Physical Specifications and Installation

Case Size: Midos specification cases (Size 6 or Size 8) are usually adopted, which is convenient for insertion into standard bases.

Indicator light (LED) : The panel is equipped with an independent LED indicator light, which is used to indicate the “start” or “trip” status of two-phase and ground faults.

Maintainability: Supports online testing mode, allowing the health status of the relay to be tested through the panel buttons without disconnecting the circuit.

MCGG52H1CB0753C

4. Common Applications

Distribution line protection: Applicable to overload and short-circuit protection of medium and low voltage overhead lines or cable feeders.

Transformer backup protection: As a backup overcurrent protection for the high-voltage or low-voltage side of power transformers.

Motor protection: Provides reliable protection against locked rotor and ground faults of large motors

Technical indicators of parameter items

The number of protected phases is 2 for overcurrent and 1 for grounding

Secondary rated current: 1A

The auxiliary DC voltage is 48/125V DC

The instantaneous breaking factor is set at 1 to 31 times the current

Industrial-grade protection that complies with IEC standards