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ASL-441H line protection relay
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
27/ 50/ 51/ 67/ 25/ 79/ 46/81/ 50N/51N/ 59N/ 51I / 51NG/ 49/ 62/ 50HS / 60
Communication Mode:Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 (IEC-103)
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Description
The ASL-441H is a multifunction numerical line protection relay designed for overhead lines and cable feeders in power distribution and substation systems. It integrates overcurrent, directional overcurrent, ground fault, auto-reclosing, underfrequency load shedding and voltage-related protection functions in a single relay. The device is designed for low-current grounding systems with ungrounded or arc-suppression-coil-grounded neutral points and is suitable for line applications up to 66 kV.
Overview
ASL-441H Line Protection Relay
Multifunction numerical protection for overhead lines and cable feeders up to 66 kV
Key Features
- Overcurrent and directional overcurrent protection
- Zero-sequence overcurrent and overvoltage protection
- Auto-reclosing and synchronism check
- Underfrequency load shedding
- Small-current grounding line selection
- CT/PT circuit supervision
- Event logging and fault recording
- RS-485, Ethernet and IEC 60870-5-103 communication
Application
Distribution substations · Medium-voltage lines · Cable feeders · Overhead lines · Low-current grounding systems
Protection Functions
Overcurrent and Directional Protection
| Function | ANSI |
|---|---|
| Three-stage overcurrent | 50/51 |
| Directional overcurrent | 67 |
| Inverse-time overcurrent | 51I |
Ground Fault Protection
| Function | ANSI |
|---|---|
| Zero-sequence overcurrent | 50N/51N |
| Zero-sequence overvoltage | 59N |
| Small-current grounding line selection | 51NG |
Voltage, Frequency and Overload Protection
| Function | ANSI |
|---|---|
| Undervoltage | 27 |
| Overfrequency / underfrequency | 81 |
| Negative sequence | 46 |
| Overload | 49 |
Control and Supervision
| Function | ANSI |
|---|---|
| Auto-reclosing | 79 |
| Synchronism check | 25 |
| CT supervision | 60 |
| Control circuit supervision | 74 |
| SOTF / high-speed closing protection | 50HS |
| Bus charging protection | 62 |
ASL-441H Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | ASL-441H |
| Device Type | Numerical line protection relay |
| Application Voltage | ≤66 kV |
| Grounding System | Ungrounded / arc-suppression-coil grounded |
| Protection Functions | 50/51, 67, 50N/51N, 59N, 79, 81, etc. |
| Communication | RS-485 / CAN / Ethernet |
| Protocol | IEC 60870-5-103 |
| Protection Response Time | ≤35 ms* |
| Current Accuracy | ±2.5%* |
| Voltage Accuracy | ±3%* |
| Measurement Accuracy | I/U Class 0.2; P/Q Class 0.5 |
| Fault Recording | Supported |
ASL-441H Applications
The ASL-441H is a multifunction numerical line protection relay designed for overhead lines and cable feeders up to 66 kV. It is not intended for EHV transmission systems, but serves as a comprehensive protection solution for medium-voltage distribution networks and industrial power systems.
| Application | Key Features | Typical Users |
|---|---|---|
| Medium-Voltage Distribution Lines | Overcurrent, directional, zero-sequence | Utilities, industrial plants |
| Substation Feeder Protection | Directional overcurrent, breaker failure | Utilities, EPC contractors |
| Overhead Line Protection | Auto-reclosing, earth fault detection | Utilities, renewable projects |
| Cable Feeder Protection | High-speed tripping, fault recording | Industrial, commercial networks |
| Low-Current Grounding Systems | Small-current grounding line selection | Utilities, mining, offshore |
| Power Distribution Automation | IEC 60870-5-103, SCADA integration | System integrators, utilities |
Grounding System Compatibility
The ASL-441H is designed for low-current grounding systems, including networks with ungrounded neutral points and neutral points grounded through arc-suppression coils. The grounding method should be confirmed when selecting protection functions and configuring zero-sequence protection.
Communication and SCADA Integration
| Interface | Application |
|---|---|
| RS-485 | Local/serial communication |
| CAN | Device communication |
| Ethernet | Network communication |
| IEC 60870-5-103 | Substation protection communication |
The relay can exchange protection status, measurements, alarms, events and fault information with a substation automation or SCADA system through supported communication interfaces.
Event Logging and Fault Recording
Event Records
- Protection trip
- Device malfunction
- Trip time
- Operating parameters
Fault Recording
- Fault operation time
- Protection type
- RMS values
- Pre-fault data
- Post-fault data
SOE
48 sets retained after power loss
Fault Reports
16 sets retained after power loss
Line Protection Device — Outline and Installation Dimensions
ASL-441H Line Protection Relay – FAQ
Q 1: What is the ASL-441H line protection relay?
The ASL-441H is a multifunction numerical line protection relay designed for overhead lines and cable feeders up to 66 kV. It provides complete phase and earth fault protection, auto-reclosing, frequency protection, and small-current grounding line selection—making it suitable for distribution substations, medium-voltage lines, and industrial power networks.
Q 2: What voltage level is the ASL-441H suitable for?
The ASL-441H is designed for systems up to 66 kV, covering medium-voltage distribution networks. It is not intended for EHV transmission systems but serves as a comprehensive protection solution for 10kV to 66kV overhead lines, cable feeders, and substation outgoing feeders.
Q 3: What protection functions does the ASL-441H provide?
| Function | Description |
|---|---|
| Overcurrent (50/51) | Phase overcurrent protection |
| Directional Overcurrent (67) | Directional phase overcurrent for loop networks |
| Zero-Sequence Overcurrent (50N/51N) | Earth fault protection |
| Zero-Sequence Overvoltage (59N) | Detects earth faults in isolated/compensated systems |
| Auto-Reclosing (79) | Automatic supply restoration after transient faults |
| Synchronism Check (25) | Ensures safe reclosing conditions |
| Underfrequency Load Shedding (81U) | Frequency protection for load shedding |
| Small-Current Grounding Line Selection | Identifies faulty feeder in low-current grounding systems |
| CT/PT Supervision | Detects CT/PT circuit failures |
| Event Logging & Fault Recording | Captures fault data for analysis |
Q 4: Can the ASL-441H be used in ungrounded or arc-suppression-coil grounded systems?
Yes. The ASL-441H is specifically designed for low-current grounding systems, including isolated neutral and arc-suppression-coil (Petersen coil) grounded networks. Its small-current grounding line selection function detects earth faults in such systems, enabling selective fault isolation without unnecessary supply interruptions.
Q 5: What communication protocols does the ASL-441H support?
The ASL-441H supports the following communication interfaces and protocols:
| Interface | Application |
|---|---|
| RS-485 | Local SCADA and HMI connectivity |
| CAN | Device-to-device communication |
| Ethernet | High-speed SCADA and engineering access |
| IEC 60870-5-103 | Standard substation automation protocol |
Q 6: Does the ASL-441H support auto-reclosing and synchronism check?
Yes. The ASL-441H includes:
-
Auto-reclosing (ANSI 79) – Automatically restores supply after transient faults. Multiple reclose shots can be configured according to project requirements.
-
Synchronism check (ANSI 25) – Ensures voltage, frequency, and phase angle match before reclosing, preventing mechanical stress and system disturbances.
Q 7: What information is required to configure an ASL-441H relay?
To configure an ASL-441H relay, the following information is required:
-
System voltage level (10kV–66kV)
-
CT and PT primary/secondary ratings
-
Line and feeder configuration (radial, loop, multi-source)
-
Required protection functions (overcurrent, directional, earth fault, etc.)
-
Auto-reclosing sequence requirements
-
Communication protocol and SCADA integration requirements
-
Coordination settings with upstream/downstream protection
Settings should be calculated by qualified protection engineers based on system fault levels and coordination studies.
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