Description

Table of Contents

Overview

The ASL-441H Digital Line Protection and Monitoring Unit, as one of the professional transmission line protection relays and digital relays for transmission line protection, is a high-performance line protection relay suitable for low-current grounding systems with ungrounded neutral points or neutral points grounded via arc-suppression coils at voltage levels of 66 kV and below. It serves as bay-level equipment for line units.

Protection Functions and Corresponding ANSI Codes

Three-stage Definite-time Overcurrent Protection

Function Description: Includes instantaneous overcurrent trip, delayed instantaneous trip and regular overcurrent protection. All three stages support undervoltage blocking and directional blocking, with independent enable and disable functions.
ANSI Code: 27, 50, 51, 67

Auto-reclosing Protection

Function Description: Supports three-phase single-shot auto-reclosing, reclosing post-acceleration, reclosing synchronism check, dead-line voltage check and current blocking reclosing functions.
ANSI Code: 25, 79

Under-frequency Load Shedding Protection

Function Description: Equipped with slip blocking, undercurrent blocking and undervoltage blocking, which can be enabled or disabled independently. The output supports configurable trip (reclosing blocking) or alarm mode.
ANSI Code: 27, 46, 81

Zero-sequence Overcurrent Protection

Function Description: Supports configurable trip or alarm output.
ANSI Code: 50N / 51N

Zero-sequence Overvoltage Protection

Function Description: Supports configurable trip or alarm output.
ANSI Code: 59N

Inverse-time Overcurrent Protection

Function Description: Provides inverse-time overcurrent protection characteristic.
ANSI Code: 51I

Small-current Grounding Line Selection Function

Function Description: Realizes fault line selection for small-current grounding system.
ANSI Code: 51NG

Overload Protection

Function Description: Prevents equipment damage caused by continuous overload operation.
ANSI Code: 49

Bus Charging Protection

Function Description: Provides fast protection during busbar charging operation.
ANSI Code: 62

Loss of Voltage Protection

Function Description: Detects system undervoltage and loss of voltage fault.
ANSI Code: 27

CT Disconnection Fault Detection

Function Description: Monitors and identifies current transformer circuit disconnection fault.
ANSI Code: 60

Manual Closing and Reclosing Post-acceleration Protection

Function Description: Triggers accelerated tripping during manual closing and auto-reclosing operation.
ANSI Code: 50HS

Control Circuit Disconnection Detection

Function Description: Detects disconnection fault of device control circuit.
ANSI Code: 74

PT Disconnection Fault Detection

Function Description: Monitors and identifies voltage transformer circuit disconnection fault.
ANSI Code: 60

Communication Mode

Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 (IEC-103)

Main Functional Specifications

Protection response time (including the response time of the output relay): Average error in response time: not more than 35 ms;
Precision operating range: Minimum precision current: 0.08 In, Maximum precision current: 20 In
Current setting error: When the current exceeds 1.00 A, the error shall not exceed ±2.5%; Voltage setting error: shall not exceed ±3%
Measurement accuracy: Current (I)/Voltage (U): Class 0.2; Power (P)/Reactive power (Q): Class 0.5
Remote signal resolution: no more than 2 ms

Event Logging, Fault Recording

The recorded events include protective action events and device malfunctions;
Record the type of protection trip, the time of the trip, and the operating parameters at the time of the trip;
The fault recording data includes: the time of the protection operation, the type of protection operation, and the rms values before and after the recording was initiated;
Data length of the fault recording: 2 cycles before the fault and 4 cycles after the fault;
The SOE can retain 48 sets of data after a power loss, and the fault report can retain 16 sets of data after a power loss.

Monitoring Features

The device is capable of measuring analog quantities such as current, voltage, and frequency;
Collect position signals from circuit breakers, energy storage systems, isolating switches, and remote/local control switches, as well as other digital signals;
Control functions of the disconnect switch.

Setting Table

Parameter No.	Parameter Name	Range	Step	Remarks
1. Primary Stage Overcurrent Setting	–	–	–	–
1.1	Primary Stage Protection Enable/Disable	1 / 0	–	1: Enable primary stage protection; 0: Disable primary stage protection
1.2	Primary Stage Undervoltage Blocking Enable/Disable	1 / 0	–	1: Enable undervoltage blocking; 0: Disable undervoltage blocking. Correlates with general undervoltage blocking settings (Item 11)
1.3	Primary Stage Directional Blocking Enable/Disable	1 / 0	–	1: Enable directional blocking; 0: Disable directional blocking
1.4	Primary Stage Post-Acceleration Enable/Disable	1 / 0	–	1: Enable post-acceleration; 0: Disable post-acceleration. Correlates with post-acceleration time setting (Item 11)
1.5	Primary Stage Time Delay	0.10～120.00s	0.01s	–
1.6	Primary Stage Current Setting Value	0.40～99.99A (In=5A)0.10～20.00A (In=1A)	0.01A	Rated current adaption
2. Secondary Stage Overcurrent Setting	–	–	–	–
2.1	Secondary Stage Protection Enable/Disable	1 / 0	–	1: Enable secondary stage protection; 0: Disable secondary stage protection
2.2	Secondary Stage Undervoltage Blocking Enable/Disable	1 / 0	–	1: Enable undervoltage blocking; 0: Disable undervoltage blocking. Correlates with general undervoltage blocking settings (Item 11)
2.3	Secondary Stage Directional Blocking Enable/Disable	1 / 0	–	1: Enable directional blocking; 0: Disable directional blocking
2.4	Secondary Stage Post-Acceleration Enable/Disable	1 / 0	–	1: Enable post-acceleration; 0: Disable post-acceleration. Correlates with post-acceleration time setting (Item 11)
2.5	Secondary Stage Time Delay	0.10～120.00s	0.01s	–
2.6	Secondary Stage Current Setting Value	0.40～99.99A (In=5A)0.10～20.00A (In=1A)	0.01A	Rated current adaption
3. Tertiary Stage Overcurrent Setting	–	–	–	–
3.1	Tertiary Stage Protection Enable/Disable	1 / 0	–	1: Enable tertiary stage protection; 0: Disable tertiary stage protection
3.2	Tertiary Stage Undervoltage Blocking Enable/Disable	1 / 0	–	1: Enable undervoltage blocking; 0: Disable undervoltage blocking. Correlates with general undervoltage blocking settings (Item 11)
3.3	Tertiary Stage Directional Blocking Enable/Disable	1 / 0	–	1: Enable directional blocking; 0: Disable directional blocking
3.4	Tertiary Stage Post-Acceleration Enable/Disable	1 / 0	–	1: Enable post-acceleration; 0: Disable post-acceleration. Correlates with post-acceleration time setting (Item 11)
3.5	Tertiary Stage Time Delay	0.10～120.00s	0.01s	–
3.6	Tertiary Stage Current Setting Value	0.40～99.99A (In=5A)0.10～20.00A (In=1A)	0.01A	Rated current adaption
4. Zero-sequence Overcurrent Setting	–	–	–	–
4.1	Zero-sequence Primary Stage Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
4.2	Zero-sequence Secondary Stage Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
4.3	Zero-sequence Primary Stage Output Mode	1 / 0	–	1: Trip; 0: Alarm
4.4	Zero-sequence Secondary Stage Output Mode	1 / 0	–	1: Trip; 0: Alarm
4.5	Zero-sequence Directional Blocking Enable/Disable	1 / 0	–	1: Enable blocking; 0: Disable blocking
4.6	Small-current Grounding Line Selection Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
4.7	Zero-sequence Primary Stage Time Delay	0.10～120.00s	0.01s	–
4.8	Zero-sequence Secondary Stage Time Delay	0.10～120.00s	0.01s	–
4.9	Zero-sequence Primary Stage Current Setting	0.10～5.00A	0.01A	–
4.10	Zero-sequence Secondary Stage Current Setting	0.10～5.00A	0.01A	–
5. Zero-sequence Overvoltage Setting	–	–	–	–
5.1	Zero-sequence Overvoltage Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
5.2	Zero-sequence Overvoltage Output Mode	1 / 0	–	1: Trip; 0: Alarm
5.3	Zero-sequence Overvoltage Time Delay	0.10～120.00s	0.01s	–
5.4	Zero-sequence Overvoltage Setting Value	5.00～100.00V	0.01V	–
6. Loss of Voltage Protection Setting	–	–	–	–
6.1	Loss of Voltage Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
6.2	Loss of Voltage Output Mode	1 / 0	–	1: Trip; 0: Alarm
6.3	Loss of Voltage Time Delay	0.10～120.00s	0.01s	–
6.4	Loss of Voltage Setting Value	5.00～100.00V	0.01V	–
7. Auto-reclosing Setting	–	–	–	–
7.1	Auto-reclosing Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
7.2	Dead-line Voltage Check Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
7.3	Synchronism Check Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
7.4	Synchronism Voltage Selection	1 / 0	–	1: Phase voltage Ua; 0: Line voltage Uab
7.5	Current Blocking Reclosing Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
7.6	Auto-reclosing Time	0.10～120.00s	0.01s	–
7.7	Dead-line Voltage Setting Value	5.00～100.00V	0.01V	–
7.8	Synchronism Angle Setting	10°～50°	1°	–
8. Overload Protection Setting	–	–	–	–
8.1	Overload Protection Enable/Disable	1 / 0	–	1: Enable overload alarm; 0: Disable overload alarm
8.2	Overload Time Delay	0.10～120.00s	0.01s	–
8.3	Overload Current Setting Value	0.40～99.99A (In=5A)0.10～20.00A (In=1A)	0.01A	Rated current adaption
9. Under-frequency Load Shedding Setting	–	–	–	–
9.1	Under-frequency Load Shedding Enable/Disable	1 / 0	–	1: Enable function; 0: Disable function
9.2	Under-frequency Load Shedding Output Mode	1 / 0	–	1: Trip; 0: Alarm
9.3	Frequency Slip Blocking Enable/Disable	1 / 0	–	1: Enable blocking; 0: Disable blocking
9.4	Under-current Blocking for Frequency Protection Enable/Disable	1 / 0	–	1: Enable blocking; 0: Disable blocking
9.5	Under-voltage Blocking for Frequency Protection Enable/Disable	1 / 0	–	1: Enable blocking; 0: Disable blocking
9.6	Load Shedding Time Delay	0.10～120.00s	0.01s	–
9.7	Current Blocking Setting Value	0.20～10.00A	0.01A	–
9.8	Frequency Protection Voltage Blocking Value	5.00～100.00V	0.01V	Setting value for undervoltage blocking of frequency protection
9.9	Frequency Setting Value	46.00～50.00Hz	0.01Hz	–
9.10	Frequency Slip Setting Value	0.00～9.99Hz/s	0.01Hz/s	ΔF/ΔT, frequency change rate
10. Inverse-time Overcurrent Setting	–	–	–	–
10.1	Inverse-time Overcurrent Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
10.2	Time Constant	0.10～120.00s	0.01s	Time constant for inverse-time overcurrent protection
10.3	Inverse-time Current Setting Value	0.50～10.00A (In=5A)0.20～2.00A (In=1A)	0.01A	Rated current adaption
11. Bus Charging Protection Setting	–	–	–	–
11.1	Bus Charging Protection Enable/Disable	1 / 0	–	1: Enable protection; 0: Disable protection
11.2	Bus Charging Current Setting Value	0.00～99.99A	0.01A	–
12. CT Disconnection Setting	–	–	–	–
12.1	CT Disconnection Alarm Enable/Disable	1 / 0	–	1: Enable alarm; 0: Disable alarm
12.2	CT Disconnection Setting Value	0.10～5.00A	0.01A	–
12.3	CT Disconnection Time Delay	0.10～120.00s	0.01s	–
12.4	Live Current Setting Value	0.05A～5.00A	0.01A	–
13. General Setting	–	–	–	–
13.1	PT Disconnection Alarm Enable/Disable	1 / 0	–	1: Enable alarm; 0: Disable alarm
13.2	Blocking Release upon PT Disconnection	1 / 0	–	1: Release all blocking; 0: Retain blocking protection
13.3	Control Circuit Disconnection Alarm Enable/Disable	1 / 0	–	1: Enable alarm; 0: Disable alarm
13.4	Voltage Wiring Mode	1 / 0	–	1: Three-phase four-wire; 0: Three-phase three-wire
13.5	Rated Current Adaptation	1 / 0	–	1: 1A rated current; 0: 5A rated current
13.6	Rated Voltage Adaptation	1 / 0	–	1: 380V voltage level; 0: 100V voltage level
13.7	B17 Maintenance Plate Enable/Disable	1 / 0	–	1: Enable maintenance plate; 0: Disable maintenance plate
13.8	Energy Integration Calculation Enable/Disable	1 / 0	–	1: Enable calculation; 0: Disable calculation
13.9	Harmonic Component Calculation Enable/Disable	1 / 0	–	1: Enable calculation; 0: Disable calculation
13.10	Overcurrent Undervoltage Blocking Threshold	5.00～100.00V	0.01V	Valid for 1st, 2nd and 3rd stage undervoltage blocking functions
13.11	Post-acceleration Time	0.10～120.00s	0.01s	Applied to 1st, 2nd and 3rd stage post-acceleration functions
13.12	Mutation Startup Current Setting	0.00～9.99A	0.01A	–

Line Protection Device — Outline and Installation Dimensions

Front View Dimension Drawing of the Generator Backup Protection Device Side Dimension Drawing of the Generator Backup Protection Device

FAQ

Q：what is line level device protection?

A:Line Level Device Protection refers to protection functions and device configurations deployed at the individual line level in a power distribution/substation system.

Q：How to Select Relay Protection for Power Transmission Lines?

A:Transmission line protection devices commonly adopt line protection with overcurrent relays for most transmission line protection systems, specifically three-stage current protection. For higher voltage scenarios, transmission line protection using distance relay together with optical fiber differential protection is applied to safeguard transmission lines.

Q：What is the effect of nonlinear loads on the operation of protective devices?

A:The resulting effects include harmonic distortion, voltage stability issues, and power factor problems, among others

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ASL-441H line protection relay

Description

Overview

Protection Functions and Corresponding ANSI Codes

Three-stage Definite-time Overcurrent Protection