Year: 2026

The MCTI40F1AB0751F of GEC ALSTHOM is a high-precision and high-performance microcomputer-based Overcurrent protection Relay.

It belongs to the MCTI family of the Midos series and is specifically designed for monitoring and protecting against abnormal currents in power systems.

The following is the detailed product information and parameter analysis of this model:

1. Core technical Specifications and Parameters Technical Indicators Product Model MCTI40F1AB0751F Protection Function Single-phase Overcurrent Protection (Single Phase Overcurrent) Rated Current ($I_n$)1A / 5A on-site selectable (usually selected through internal jumpers or terminals) Auxiliary power supply 110V The -125V DC (code ‘B’) frequency 50/60Hz universal measurement features offer time-limited (DT) and multiple inverse-time (IDMT) curve options

2. Explanation of the Meaning of model codes

MCTI: Brand series code, representing digital/microcomputer type current protection relay.

40: Function code. MCTI 40 usually refers to having single-phase measurement capability and supporting standard inverse-time characteristics.

F: Inverse-time characteristic code. Support Standard curves such as SI (Standard Inverse), VI (Very Inverse), EI (Extremely Inverse), etc.

1: Hardware version or specific application code.

A: Installation form, standard Midos Size 2 embedded installation.

B: Auxiliary voltage rating, corresponding to the industrial standard 110/125V DC.

0751F: Factory-specific configuration code, which defines the software version and preset logic

3. Main Functional features

MCTI40F1AB0751F

High sampling accuracy: Utilizing digital signal processing technology, compared with the old electromagnetic relays, it measures more accurately and is less affected by environmental temperature.

Multiple characteristic curves: Through the dip switches or buttons on the relay panel, users can set different action curves (such as IEC or ANSI standards) to achieve coordination with the upper and lower protection levels.

MCTI40F1AB0751F

Two-level protection: instantaneous and delayed

Low Set element: Used for overload or minor short circuit, in conjunction with delay curves.

High Set component: Used for severe short circuits, it performs rapid tripping without delay.

Status indication: Equipped with LED signs. Once an action occurs, even if the auxiliary power supply is lost, the Trip Flag usually remains until manually reset.

4. Wiring and installation of the chassis: It adopts the classic plug-in structure of the Midos series. The secondary circuit test can be conducted through a dedicated test plug without cutting off the primary current.

Typical terminal layout

13-14: Secondary input of current transformer (CT). 27-28: DC auxiliary power input ($V_x$). Output contacts: Usually one or two pairs of normally open contacts, used to drive tripping circuits

5. Application scenarios

MCTI 40 is mainly used in the following fields:

Medium-voltage feeder protection: As the main protection against overcurrent and short circuit in power distribution lines.

Transformer backup protection: As a backup protection for transformers, it prevents equipment damage caused by external short circuits.

Capacitor bank protection: Monitor phase current imbalance or overcurrent caused by faults.

ALSTOM VAJX11BP5243BA   Trip Relay for Protection Panels

The ALSTOM VAJ series has long been a go-to for robust tripping and auxiliary functions in protection schemes.

The model VAJX11BP5243BA fits that lineage: a fast, heavy-duty relay typically used to drive circuit breaker trip coils, seal-in logic, and interlock signals in substations and industrial switchgear.

From my experience, it drops right into legacy ALSTOM/AREVA panels and tends to play nicely with modern retrofit cabinets too, which keeps project risk low.

Key Features

VAJX11BP5243BA

High-speed trip duty – Designed for protection schemes where milliseconds matter;

typically used to operate breaker trip coils or seal-in circuits.

Heavy make/break capability – Handles inductive loads reliably, which you’ll notice reduces nuisance contact wear in many cases.

Dry contact outputs – Clean changeover contacts suitable for low-level signalling and higher duty trip circuits.

Proven VAJ platform – A long-standing ALSTOM design still favored for retrofit projects where compatibility and predictable performance are key.

Panel/draw-out mounting – Typically supplied in a flush-mount/draw-out case with screw terminals for straightforward panel integration and service.

Coil options for DC control – Commonly 110 V DC in utility panels;    other coils exist across the VAJ family, so we confirm against the relay label before shipping.

Technical Specifications

Brand / Model    ALSTOM VAJX11BP5243BA (VAJ series auxiliary/tripping relay)

VAJX11BP5243BA

HS Code    8536.49 (Relays, for voltage > 60 V)

Power Requirements    DC coil, typically 110 V DC across VAJ builds;    confirm coil voltage from product label

Signal I/O Types    Coil input;    dry contact outputs (changeover contacts common to VAJ series)

Communication Interfaces    None (discrete relay)

Installation Method    Panel/flush mounting in draw-out case;    screw terminals for wiring

Operating Temperature    Typically −10 to +55 °C for VAJ family relays

Dimensions & Weight    Approx. 170 × 110 × 160 mm;    ~2–3 kg (varies by exact variant)

Application Fields

You’ll typically see the VAJ series in transmission and distribution substations, power plant switchboards, industrial MCCs, and OEM protection panels.

Common tasks include trip coil actuation from protective relays, breaker fail and seal-in logic, interlocking, DC control signal duplication, and alarm fan-out.

One thing I appreciate is how consistently it behaves with inductive loads in breaker trip circuits—saves time during FAT/SAT.

GEC ALSTHOM  MVAJ53H1LB0856A Heavy-duty auxiliary tripping relay

Brand / Model ALSTOM MVAJ53H1LB0856A (MVAJ series tripping relay)

HS Code 8536.49 (Relays, other than for ≤60 V)

Function Auxiliary/tripping relay with hand‑reset latch and mechanical indication

Power Requirements DC coil (variant‑dependent; commonly supplied in 110 V DC or 220/250 V DC).   We verify the exact coil rating on the nameplate before shipment.

Signal I/O Types Mechanical trip contacts for breaker coils and interlocking (NO/NC per variant);   coil input from protection device trip output

Operate / Reset Fast operate (typically single‑digit milliseconds under rated voltage);   hand‑reset latch with visible flag

Communication Interfaces None (electromechanical device)

Installation Method Panel flush‑mount, draw‑out relay case with screw terminals;   front hand reset and flag

Operating Temperature Typically −10 °C to +55 °C for this series

Dimensions & Weight Standard ALSTOM draw‑out relay case (commonly the E‑series footprint used in protection panels);   weight is typically in the 1.5–2.0 kg range depending on element count.

The ALSTOM MVAJ53H1LB0856A is part of the well‑known MVAJ family of attracted‑armature auxiliary and tripping relays.

From my experience, this series is often chosen to interpose between protection elements and circuit-breaker trip coils, especially where a fast, robust, and visible hand-reset latch is preferred.

One thing I appreciate is how it fits legacy panels without drama—draw‑out construction, clear mechanical indication, and contacts that are genuinely built for switching trip duty.

In many cases it ends up as the “go‑to” device for trip multiplication, interlocking, and breaker fail schemes across substations, power plants, and heavy industry.

Key Features

MVAJ53H1LB0856A

Attracted‑armature tripping design – Built for dependable trip duty in protection schemes with fast operate characteristics.

Hand‑reset latch with target – Mechanical flag gives a clear, non‑volatile indication;   hand reset avoids inadvertent re‑energization.

High‑capacity contacts – Suited for circuit breaker trip coils;   typically used to multiply outputs from protection relays.

Low burden on protection elements – Coil burden is kept reasonable so upstream protection contacts aren’t overstressed.

Draw‑out, panel‑mount case – Makes installation and replacement straightforward in existing relay panels.

No communication dependency – Purely electromechanical;   immune to network or firmware issues.

Legacy compatibility – Often drop‑in compatible with existing GEC/ALSTOM installations, which typically keeps retrofit costs down.

Technical Specifications

MVAJ53H1LB0856A

Brand / Model    ALSTOM MVAJ53H1LB0856A (MVAJ series tripping relay)

HS Code    8536.49 (Relays, other than for ≤60 V)

Function    Auxiliary/tripping relay with hand‑reset latch and mechanical indication

Power Requirements    DC coil (variant‑dependent; commonly supplied in 110 V DC or 220/250 V DC).   We verify the exact coil rating on the nameplate before shipment.

Signal I/O Types    Mechanical trip contacts for breaker coils and interlocking (NO/NC per variant);   coil input from protection device trip output

Operate / Reset    Fast operate (typically single‑digit milliseconds under rated voltage);   hand‑reset latch with visible flag

Communication Interfaces    None (electromechanical device)

Installation Method    Panel flush‑mount, draw‑out relay case with screw terminals;   front hand reset and flag

Operating Temperature    Typically −10 °C to +55 °C for this series

Dimensions & Weight    Standard ALSTOM draw‑out relay case (commonly the E‑series footprint used in protection panels);   weight is typically in the 1.5–2.0 kg range depending on element count.

Application Fields

You might notice that the MVAJ53 variants show up all over the grid.   Typical uses include:

Substation protection tripping – interposing between distance, differential, or O/C relays and CB trip coils

Trip multiplication and interlocking – distributing a single protection output to multiple breakers

Breaker fail and lockout schemes – where a latched, hand‑reset action is preferred

Power plants and heavy industry – turbine‑generator and transformer protection auxiliaries

Oil & gas, mining, metals – harsh environments where a simple, visible, and testable trip element is valued

“We swapped in MVAJ relays during a feeder panel refurbishment.

The hand reset target makes post‑event checks quicker, and the draw‑out case saved us time on replacement.”   – Protection supervisor, utility client

Advantages & Value

Reliability – A simple electromechanical mechanism that, in many cases, outlasts the surrounding equipment with routine maintenance.

Compatibility – Fits established ALSTOM/GEC panel standards,

ALSTOM MVTT14B1BA0773C Current monitoring and traction transformer control module

SPECIFIC PARAMETERS

Brand ALSTOM

Product Series MVTT Series Industrial-grade Current Monitoring and Traction Transformer Control Modules

Product Type High-precision Current Monitoring + Transformer Control Integrated Module

Model MVTT14B1BA0773C

Channel Configuration 8-channel AI + 4-channel AO + 12-channel DI + 8-channel DO

Analog Input 0-5A/4-20mA (current signal) 16-bit resolution 250Hz/channel sampling rate

Analog Output 4-20mA/0-10V 16-bit resolution ±0.02% FS output accuracy

Digital Input 24VDC wet contacts  response time

Digital Output 24VDC/12A Supports 22kHz PWM pulse output

Working Voltage 24VDC±15% Dual redundant power input

Working Temperature -40℃ to 90℃

Storage Temperature -55℃ to 105℃

Relative Humidity 5%-95% Non-condensing

Protection Level IP65 (Module-level)

Installation Method Bolt-fixed Standard traction transformer control cabinet mounting holes

Size 180mm×160mm×75mm (L×W×H)

Weight 2.8kg

MVTT14B1BA0773C

Power Consumption Typical 16W Maximum 22W

Compatible Systems ALSTOM MITRAC control system Rail transit TCMS Industrial DCS/SCADA Traction transformer control system Power equipment monitoring platform

Diagnostic Functions Current over-limit alarm Transformer temperature monitoring Channel fault self-diagnosis Overload/short-circuit protection Power supply abnormality diagnosis Communication link monitoring

Anti-interference Level Complies with EN 50121-3-2/EN 61000-6-2 standards

Vibration/Shock Resistance Complies with IEC 61373 Class 3 standard (Rail transit grade)

MTBF ≥2.000.000 hours

Housing Material Aviation-grade high-strength aluminum alloy + metal shield Fully sealed structure

Communication Interfaces Ethernet/IP CANopen Profibus DP Supports Modbus TCP

Programming Environment ALSTOM Control Suite Supports IEC 61131-3 standard languages

Clock Synchronization Supports IRIG-B/PTP Synchronization accuracy ±0.08ms

Insulation Resistance ≥250MΩ (1000VDC)

Channel Isolation 3500Vac electrical isolation between input/output/power

Measurement Accuracy Current measurement error ≤±0.02% FS

PRODUCT PERFORMANCE

MVTT14B1BA0773C

Enhanced multi-channel configuration covers the full link of current acquisition, control and transformer condition monitoring, adapting to complex traction power supply logic

16-bit high resolution and ±0.02% FS ultra-high measurement accuracy, 250Hz high sampling rate realizes millisecond-level precise capture of current parameters

Wide current input range adapts to transformers of different power levels, measurement error ≤±0.02% FS, ensuring absolute reliability of monitoring data

-40℃ to 90℃ wide temperature adaptability, withstanding high temperature, alpine, high humidity and strong electromagnetic radiation working conditions on-board and industrial sites

IP65 fully sealed protection and high-strength aluminum alloy housing, providing excellent dustproof, waterproof, corrosion-resistant and vibration/shock-resistant performance

3500Vac high electrical isolation design, effectively resisting strong electromagnetic interference and voltage surges in traction systems, ensuring stable signal transmission

Dual redundant power input design, resisting power fluctuations and single power failure, ensuring uninterrupted operation of the module

Multi-protocol industrial bus compatibility, supporting cross-system linkage and flexible access to various control platforms, adapting to distributed monitoring needs

Deeply compatible with ALSTOM MITRAC control system, simplifying system integration, debugging and later operation/maintenance processes

SIL 2 functional safety level, built-in dual protection mechanisms of overload and short circuit, responding to faults in milliseconds and cutting off dangerous circuits to protect equipment safety

GEC ALSTHOM Communication module 3BE101

Efficient communication:

The module supports a variety of communication protocols and interface standards, and can quickly communicate and exchange data with various industrial automation equipment and sensors to achieve efficient data transmission and control.

3BE101

High reliability:

The module uses high-quality materials and manufacturing processes, and has high reliability and stability after strict quality control and testing, which can ensure long-term continuous operation.

Programmability:

The module supports control and configuration through the programming interface, which is convenient for users to customize and control according to different application requirements.

ALSTHOM 3BE101 Communication control module

3BE101

Product features:

1. Efficient communication:

The module supports a variety of communication protocols and interface standards, and can quickly communicate and exchange data with various industrial automation equipment and sensors to achieve efficient data transmission and control.

2. High reliability:

The module uses high-quality materials and manufacturing processes, and has high reliability and stability after strict quality control and testing, which can ensure long-term continuous operation.

3. Programmability:

The module supports control and configuration through the programming interface, which is convenient for users to customize and control according to different application requirements.

4. High security:

The module has a security protection function, which can prevent illegal access and attacks to ensure the security of the control system.

5. Strong compatibility:

The module is compatible with a variety of different communication protocols and interface standards, and can communicate and exchange data with various industrial automation equipment and sensors, which is convenient for users to integrate and expand.

the ALSTHOM 3BE101 communication module is an efficient, reliable, programmable and secure communication control device for a variety of industrial automation applications that require the acquisition, processing and control of signals

The MVAA14B1AA0785C of GEC ALSTHOM is a high-performance Auxiliary Relay, belonging to the Midos series.

Unlike the previously mentioned MVAJ operated relays, the MVAA series is mainly used for signal expansion, logic control, interlocking circuits, and contact point addition.

The following is the specific product information of this model:

Technical Specifications and Code Analysis Model Series: MVAA 14

Relay type: Electrical Reset type. This means that after the relay operates, it will be locked and the initial state can only be restored by energizing the reset coil.

Rated voltage ($V_x$) : 110/125V DC (code ‘B’). This applies to the DC operating power supply of the standard power system.

MVAA14B1AA0785C

Contact configuration: MVAA 14 is typically equipped with 4 pairs of contacts (commonly 4 normally open or mixed configurations, depending on the internal wiring). Reset method: The core feature of this model (MVAA 14) is that it is only electrically reset and usually does not come with a manual reset lever (different from MVAA 13). Installation Size: Midos Size 2 chassis

2. Core Functions and Applications

Contact Multiplication: When the number of output contacts of the main protection relay (such as a microcomputer protection device) is insufficient, or the contact capacity cannot directly drive a high-current circuit, MVAA is used as an intermediate link.

Electrical interlock/logic control: Due to its electrical reset function, it is often used in circuits that require “memory” of the state. For instance, after a fault occurs and a trip is triggered, the relay remains in the operated state until the operator remotely sends a reset instruction through the control system (DCS/ background).

High reliability: It adopts an attractive armature structure, which operates smoothly and features extremely high mechanical stability and shock resistance

Model, Reset Type, common uses

MVAA 11. Self Reset, instantaneous signal transmission, no memory required

MVAA 13. manual Reset (Hand Reset), on-site fault indication and locking

MVAA 14. Electrical Reset, Remote Logical Lockout and state Holding