Woodward ESDR4 Current Differential Protection Relay

Woodward ESDR4   Current Differential Protection Relay 

Safety precautions

Warning: Before operation, read the complete manual and relevant publications, and follow the factory and safety instructions. If the equipment is modified or used beyond the specified operating limits without authorization, it may cause personal injury and property damage, and may void the warranty and certification. The prime mover should be equipped with an independent overspeed shutdown device.

Attention: Before disconnecting the battery, turn off the charging device. When handling electronic controls, release static electricity from the body and avoid contact with materials that are prone to static electricity, such as plastics. Do not touch printed circuit board components or conductors.

Relay Overview

Function: ESDR 4T is a three-phase current differential protection relay used for generators, motors, and transformers. By measuring the current on both sides of the protected object, it detects short circuits and ground faults within the protection zone, and does not operate for faults outside the zone, ensuring selective protection.

Working principle: Electrical isolation is applied to 6 measured currents, and differential current and braking current of each phase are calculated separately. When calculating, parameters such as transformer vector group, rated current, current transformer ratio, and voltage ratio are considered.

Model composition: It consists of a basic unit and various options, such as ESDR 4T01B representing a standard unit, no voltage measurement, CT input of 1A, and front board installation.

ESD protection

When handling electronic equipment, it is necessary to touch grounded metal objects to discharge static electricity, wear cotton clothes, and keep away from plastic, vinyl and foam materials.

When disassembling the printed circuit board, ensure that the device is completely powered off and only touch the edges. The new board should be stored in an anti-static bag.

Wiring (wiring)

Power supply: 24Vdc (± 25%), terminal 13 is+24V, 14 is 0V reference voltage, maximum current is 2.5mm ².

Measurement input: 6 current measurement inputs, using current transformers, the secondary side needs to be grounded, the polarity needs to be correct, terminals 25-36 are used to connect CT inputs, and the maximum current is 4mm ².

Discrete input: Terminals 17-19 are configured as off, confirm, and block inputs, with input voltages ranging from 18-250V (ac/dc) and a maximum current of 2.5mm ².

Relay output: 4 relay outputs, with configurable functions for relays 1-2, ready for operation for relay 3, warning for relay 4, maximum contact capacity of 250Vac, and maximum current of 2.5mm ².

Function Description

Differential current monitoring: divided into two levels. The first level is a warning, which can be enabled or disabled. When the warning characteristic is exceeded, text will be displayed and relay contacts will be activated; The second level is tripping, which can monitor adjustable tripping characteristics and a fixed tripping threshold relative to 100% of the rated current of the generator. The tripping characteristics have a 2% hysteresis.

Trip characteristics: According to the braking current, it is divided into three sections. The trip threshold is independent of the braking current from 0 to X12, increases with the increase of braking current from X12 to 5 × IN, and remains constant at 85% when it exceeds 5 × IN.

Electrical suppression of surge and overexcitation: using digital Fourier transform to detect second and fifth harmonics, enabling the "Stabilization Rush" function and setting the action margin to prevent false tripping.

Self monitoring: Provides a ready to operate signal through contact components, and the signal is disabled when the power supply voltage is below approximately 19Vdc or there is an internal fault.

Display and operation components

LED: including brake current, differential current, monitoring on and alarm LED, displaying the current status.

Button: There are message scrolling, selection, display scrolling, number increase, clear, and cursor movement buttons that can switch between display mode and configuration mode.

LC display screen: Two lines of 16 characters, displaying measurement values, alarm messages, and configuration parameters, with adjustable contrast.

configuration

Basic data: Language can be selected, software version can be viewed, configuration parameters need to be performed in configuration mode, and if there is no operation for 60 seconds, it will automatically return to display mode.

Configuration access: The sealing function can be enabled to protect the configuration through a five digit code, preventing unauthorized access and modification.

Relay configuration: The relay can be configured to operate in either working current or idle current mode, with parameters such as automatic confirmation, release delay, and message confirmation delay set, and warning messages assigned to the relay.

Rated data: Input the rated current of the protected object, the rated values of the high and low voltage side current transformers, and the voltage, and set the transformer vector group.

Differential protection configuration: After enabling differential protection, modify the triggering value, delay time, hysteresis of the trip characteristics, set parameters for surge and overexcitation suppression, and display harmonics.

debugging

Prerequisite: Connect the equipment according to the wiring diagram, connect a 24Vdc power supply, set parameters, and activate the display mode.

Secondary value testing: Using three-phase testing equipment to test the threshold, single phase testing systems may produce mismatched measurement values due to phase matching system elimination.

One time value debugging: Remove all testing equipment before testing to ensure that the current transformer is not open circuited, configure the system to allow for the most precise current regulation, test connection correctness, perform cyclic exchange testing, and retest after correct connection.

Appendix

Size: Display the external dimensions and installation hole positions of ESDR 4T.

Technical data: including technical parameters such as measured current, frequency, accuracy, power consumption, environmental conditions, digital inputs, relay outputs, protection functions, terminal and housing protection.

Parameter List: lists all parameters and their setting ranges and default values during the configuration process.

Service options: Provide product service options, including return for repair, packaging requirements, return authorization number, replacement parts, and ways to contact Woodward.

Characteristics of Protection Function

Differential current monitoring

Two level monitoring: the first level is a warning, which displays text and activates relay contacts when the threshold is exceeded; The second level is for tripping, which can monitor adjustable tripping characteristics (Id<IN) and a fixed threshold of 100% rated current (Id>IN), and the tripping delay can be independently set.

Has a 2% hysteresis characteristic to prevent frequent signal movements near the threshold.

Selective protection

It only operates when there is a fault within the protection zone, and does not trigger faults outside the zone. Accurate protection is achieved by measuring the current difference on both sides.

Surge and overexcitation suppression

Using digital Fourier transform (DFT) to detect 2nd (surge) and 5th (overexcitation) harmonics, enabling electrical suppression function can prevent false tripping, and action margin (10% -50%) needs to be set.

Technical parameter characteristics

Measurement and Accuracy

Supports 6 current inputs, measurement frequency 40-70Hz, accuracy Class 1, linear measurement range up to 5 × I N.

The secondary side of the current transformer supports 1A or 5A, with a rated short-time current (1s) of 100 × I N (1A) or 30 × I N (5A).

Power supply and power consumption

The power supply is 24Vdc (± 25%), with a maximum inherent power consumption of 6W, and supports wide temperature operation (operating temperature -20~70 ℃).

Output capability

4 relay outputs, contact material AgCdO, supporting resistive and inductive loads:

Resistive load: 2A@250Vac The 2A@24Vdc Wait.

Sensory load: 1A@250Vac The 0.36A@125Vdc Wait.

Configuration and operational characteristics

Flexible parameter settings

Configurable transformer vector group (such as Yd5, Dd0, etc.), rated current, CT ratio, voltage ratio and other parameters to adapt to different devices.

The tripping characteristic curve can be adjusted, including the braking current threshold (X12), differential current threshold (Y1/Y2), and delay time.

Human Computer Interaction and Display

The front panel is equipped with an LC display screen (two lines of 16 characters) and LED indicator lights (brake current, differential current, monitoring status, alarm), which display real-time measurement values and fault information.

Support switching between display mode and configuration mode through buttons (message scrolling, selection, numerical adjustment, etc.), easy to operate.

Relay function can be customized

Relays 1-2 and 4 can be configured for operating current (N.O.) or idle current (N.C.) mode, while relay 3 is fixed as a "ready to run" signal and supports automatic/manual fault confirmation.

Safety and protection features

electrostatic protection

Electronic components are sensitive to static electricity, and during operation, body static electricity must be released to avoid contact with plastic and other materials. Disassembling circuit boards must follow anti-static regulations.

Electrical safety design

Measure input electrical isolation to prevent interference; The power supply and input/output terminals support overload protection, and the terminal wiring specifications are clear (2.5mm ² or 4mm ²).

Sealing and Certification

The protection level of the front panel is IP42 (standard) or IP54 (with gasket), and the rear is IP21. It has passed CE and UL certification and is suitable for ordinary places and ship environments (GL certification).

Application scenario characteristics

Applicable object: Designed specifically for block connections of generators, motors, and transformers, forming protection zone boundaries and accurately detecting faults within the zone.

Compatibility: Supports different transformer vector groups and ratios, adapts to high/low voltage side systems through parameter configuration, and meets the requirements of complex power systems.

summarize

The ESDR 4T relay, with differential protection as its core, combines high-precision measurement, flexible configuration, anti-interference capability, and safety protection design. It is suitable for fault protection of key equipment in industrial power systems, ensuring stable system operation.