Beckwith M-2001B Digital Voltage Regulating Controller

Beckwith M-2001B Digital On Load Voltage Regulating Controller Application and Networking Guide

In the power system, on load tap changers (LTC) and line regulators are key equipment for maintaining voltage stability. Traditional analog voltage regulators (such as Westinghouse SVC/SVR, GE, etc.) have problems such as limited accuracy, lack of communication capability, and inconvenient parameter tuning. The M-2001B digital on load voltage regulation controller launched by Beckwith Electric, with a microcontroller as its core, provides high-precision voltage regulation while integrating rich communication protocols, data recording, parallel operation, and reverse power processing capabilities. It can adapt to various conversion panels to directly replace mainstream old models. This article is based on technical specifications and systematically analyzes the functional architecture, parameter settings, system integration, and networking applications of M-2001B, providing a complete reference for power engineers.

Product positioning and core advantages

M-2001B is a digital voltage regulator with microcontroller architecture, suitable for on load voltage regulating transformers and single-phase line voltage regulators. Its core advantages include:

High precision adjustment: The voltage band center can be set to 100-135V (step size 0.1V), and the bandwidth can be 1-6V (step size 0.1V), meeting the accuracy requirements of ANSI Class 1.

Flexible compensation: Supports R-X line voltage drop compensation (± 24V adjustable) and Z compensation (0~+24V), CT-VT phase angle correction 0 °~330 ° (step size 30 °).

Multiple timing modes: deterministic delay 1-120 seconds, inverse delay 1-120 seconds, and in sequential mode, the Tap interval delay can be set to 0-60 seconds.

Rich communication interfaces: dual RS-232 ports (COM1 top mounted, COM2 front mounted), optional RS-485 or fiber optic (ST interface), supporting multiple protocols such as BECO 2200, DNP3.0, MODBUS, UCA2.0, etc.

Powerful data management: real-time measurement, demand measurement (15/30/60 minutes), load recording, harmonic analysis (up to 31 times), Drag Hands with time stamps.

Multiple parallel connection methods: support circulation method (M-0115A required), external master slave, and Δ VAR ™ The law.

Reverse power processing: can be set to ignore, lock, reverse adjust, or return to neutral point.

UL certification: meets industrial safety standards.

This product can be adapted to various conversion panels, directly replacing the widely used old voltage regulating controllers in the industry without the need for large-scale modification of the panel surface.

Detailed explanation of core functions

2.1 Voltage regulation and timing logic

M-2001B continuously monitors the local voltage and compares it with the set band center and bandwidth. When the voltage deviates from the bandwidth, the timer starts:

Deterministic delay: issuing a boost or buck command after a fixed time.

Inverse time delay: The larger the deviation, the shorter the delay (similar to the overcurrent inverse time characteristic).

Sequential mode and non sequential mode:

Non sequential mode: The timer resets immediately after each voltage adjustment action, and if the voltage still exceeds the limit, the timer continues to count, allowing for rapid and continuous voltage adjustment.

Sequential mode: The timer only resets after the voltage returns to the band, ensuring sufficient interval between each action (InterTap Delay can be set) to reduce mechanical wear.

2.2 Line voltage drop compensation (LDC)

The LDC function is used to compensate for the voltage drop caused by the load current on the feeder impedance, keeping the voltage at the receiving end (load center) at the set value. M-2001B provides:

R and X compensation: adjustable ± 24V each, with a step size of 1V.

Z compensation: amplitude type compensation (0~+24V), suitable for situations where phase differentiation is not required.

CT-VT phase angle correction: Adjust the phase of the current relative to the voltage in 30 ° steps to ensure the correct compensation direction.

The compensation calculation formula is based on the measured load current and the set R/X/Z values. The controller automatically calculates and corrects the reference voltage to keep the load center voltage constant.

2.3 Voltage Limitation and Runback

M-2001B provides multiple voltage protection:

Overvoltage/undervoltage independent limit: adjustable from 95~135V, with a step size of 0.1V.

Rollback function: When the overvoltage exceeds the limit and exceeds the rollback dead zone (adjustable from 1 to 4V), the controller forces the voltage to drop to a safe range.

Tap position limit: Users can set upper and lower limits to prevent taps from exceeding the mechanical allowable range of the transformer.

2.4 Voltage Reduction

Supports up to three independent voltage reduction steps, each step can be set to 0%~10% (based on the center), suitable for night light load or energy-saving mode. It can be remotely activated/deactivated through external contacts or communication.

Reverse power detection and processing

M-2001B has reverse power detection capability and is suitable for two scenarios: transformer LTC and single-phase voltage regulator:

Transformer LTC application: Users can choose to ignore reverse power, lockout voltage regulation, reverse regulation (using independent settings), or return to neutral point.

Single phase voltage regulator: supports "keep track" tap position or "reverse adjustment" function, the latter allows bidirectional voltage regulation using reverse power signals without PT on the power side.

When reverse power is applied, the REV PWR LED on the panel lights up and the programmable alarm contact outputs.

Parallel operation and circulation control

M-2001B supports multiple parallel modes:

4.1 Circulating Current Method

The standard method requires the use of M-0115A parallel balancing module. Each controller detects the circulating current between transformers through circulating current CT. M-0115A generates a correction signal and sends it to the circulating current input of M-2001B. The controller adjusts the tap according to this to balance the circulating current.

4.2 ΔVAR ™ method

Δ VAR1: It needs to be used in conjunction with M-0115A and adjusted in parallel based on reactive power deviation.

Δ VAR2: Without the need for M-0115A, the controller can directly achieve parallel connection by exchanging reactive power information through communication, simplifying hardware configuration.

4.3 External Master Follower

Implementing instruction following for a host controller through external circuits, suitable for simple parallel scenarios.

Important: Except for Δ VAR2, it is recommended to configure overcurrent protection (such as M-0127 overcurrent relay) for all other parallel connections to prevent damage to the transformer in case of abnormal circulating current.

Communication function and networking

5.1 Communication port

COM1 (top): Optional RS-232, RS-485, or fiber optic (ST interface), supporting BECO 2200, BECO 2179, Cooper 2179, GP2179, DNP3.0, MODBUS, UCA2.0 protocols.

COM2 (front panel): RS-232 port, used for local communication and firmware upgrades, using BECO 2200 protocol.

Only one communication port is activated at the same time.

5.2 Network Topology

M-2001B supports multiple networking methods:

Point to point direct connection: Connect directly to the PC via a null modem cable (M-0423).

Remote communication via modem: Supports Hayes compatible modems for remote access via telephone network.

Fiber optic Loop: Using ST interfaces to form a fiber optic loop network, it has strong anti-interference ability and is suitable for high-voltage substations.

RS-485 bus: 2-wire multi-point network, capable of mounting multiple controllers (addresses 1-200), with a 120 Ω terminal resistor required at the end.

5.3 TapTalk Software Features

The M-2029A TapTalk communication software provides the following remote operation capabilities:

Read and modify all set values

Broadcast commands (such as voltage regulation lockout, three-step voltage reduction)

Identify alarm conditions (voltage exceeding limit, overload, etc.)

Selective control of voltage rise/fall operation

Change configuration (such as required credit cycle)

Download data records and historical information

5.4 Load recording and dragging pointer

Drag Hands: Record the minimum/maximum local voltage within 32 seconds with a time stamp.

Demand measurement: Record the maximum current, maximum active/reactive/apparent power, and corresponding power factor with time stamps on a 15/30/60 minute cycle.

Tap position recording: Record the number of times each tap position has been passed (using BECO 2200 protocol).

Input/output specifications

6.1 Input

Control voltage: 90~140Vac, 50/60Hz optional, power consumption ≤ 8VA.

Motor power supply: 120~240Vac, maximum 6A, no need to change wiring.

Line current: 0.2A rated (CT input), requiring M-0121 or M-0169 auxiliary CT to adapt to 5A/8.66A CT.

Circulating current: 0.2A rated, used for parallel operation.

6.2 Output

Boost/buck output: switchable motor power supply of 120~240Vac, maximum 6A.

Output mode: Continuous (continuous output when voltage exceeds the limit) or Pulse (programmable for 0.2~12 seconds).

6.3 Alarm Contact Points

1 programmable normally open contact

1 normally closed self-test alarm contact (activated in case of power failure or malfunction)

Contact capacity: 3A@120Vac

On site debugging and maintenance

7.1 Basic setup process

Set electrical parameters: input VT/CT ratio, rated voltage, phase angle correction.

Set voltage regulation parameters: with center, bandwidth, delay mode and value.

Configure LDC: Calculate line impedance and set R/X or Z compensation values.

Set protection limits: overvoltage/undervoltage limits, tap position limits, and rollback dead zone.

Configure output mode: Select continuous or pulse output, set pulse width.

Set parallel mode (if applicable): Select circulating current/Δ VAR/master-slave and connect the corresponding hardware.

Configure communication: Set protocol, address, and baud rate.

7.2 Common troubleshooting

Possible causes and solutions for the phenomenon

Long term deviation of voltage from the center LDC setting deviation, CT polarity error check CT wiring and phase angle correction, recalculate compensation value

The voltage regulation action is too frequent, the bandwidth is too narrow, the delay is too short, and the sequential mode is not enabled to increase the bandwidth or delay. Enable the sequential mode

Controller does not respond to voltage regulation. External locking contacts are closed, reverse power is locked, voltage limit is exceeded. Check external locking input, reverse power status, and voltage limit settings

When parallel connected, the loop current flows through the large M-0115A, and the sensitivity switch is adjusted for CT polarity reversal. Check the polarity of the CT wiring

Communication cannot be established due to protocol mismatch, address error, wiring issues. Confirm protocol settings and check address and cable connections

Design Evolution and Selection

M-2001B is the digital evolution version of the M-2001 series. Early analog controllers relied on potentiometer settings, and accuracy was affected by temperature and aging. M-2001B adopts a microcontroller and digital settings, and all parameters can be accurately programmed and saved in non-volatile memory. It also introduces new functions such as communication, data recording, and harmonic analysis.

Attention should be paid when selecting:

Confirm the secondary rated value of CT (0.2A, 1A, or 5A) and select the corresponding auxiliary CT.

Confirm the requirement for parallel connection, selecting Δ VAR2 can eliminate M-0115A.

Confirm communication interface requirements (RS-232/RS-485/fiber optic).

Confirm whether a tap position sensor (M-2025B current loop interface module) is required.