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.