The AM4 Series Protection Relay from Acrel provides comprehensive, high-speed electrical protection for low and medium-voltage systems, particularly in transformer and line applications. It integrates directional and non-directional overcurrent, earth fault, undervoltage, overvoltage, frequency, and residual voltage protection within a compact device. Featuring RS485 communication and programmable alarm logic, the AM4 Series ensures accurate fault detection, system stability, and flexible operation. Designed for panel integration, it supports real-time parameter monitoring, event logging, and remote control, making it ideal for smart substations, automation systems, and industrial energy networks.

Technical Specifications

Feature	Specification
Model	AM4 Series
Input Voltage	110V AC/DC, 220V AC/DC, 48V DC
Input Current	1A / 5A (configurable)
Protection Functions	– Overcurrent (3-stage IDMT) – Earth Fault (2-stage IDMT) – Negative Sequence Overcurrent – Overvoltage (trip/alarm) – Undervoltage (trip/alarm) – Residual Overvoltage (alarm) – Under-frequency – Overload (trip/alarm) – Auto-reclosing – PT supervision – Non-electricity protection – FC block
Measurement Parameters	Voltage (U), Current (I), Active Power (P), Reactive Power (Q), Apparent Power (S), Power Factor (PF), Frequency (F), Energy (Ep, Eq, Es)
Communication Interfaces	RS485
Protocols Supported	Modbus-RTU, IEC 60870-5-103
Event Recording	Fault recorder, Sequence of Events (SOE)
Monitoring Functions	Anti-pumping circuit, Remote control
Mounting Type	Panel-mount with cutout (approx. 164mm × 158mm)
Dimensions (WxHxD)	Approx. 205mm × 178mm × 155mm

Functions

• Advanced protection logic for lines and transformers
• Three-stage time inverse overcurrent and dual-stage earth fault detection
• Monitoring and alarm on over/undervoltage and frequency deviations
• Residual voltage monitoring and PT supervision alarms
• Automatic reclosing and anti-pumping for breaker logic control
• Real-time measurement and event recording (fault + SOE)
• Remote trip/close supervision and Modbus/IEC integration via RS485

Applications

• Substation and distribution transformer protection
• Industrial switchgear panel protection systems
• Backup relay for power automation and smart grid
• Busbar and line differential backup schemes
• Energy-intensive manufacturing or process control plants

Manufacturer Information

Acrel Co., Ltd., established in 2003, is a high-tech enterprise specializing in energy efficiency management and electrical safety solutions. With a comprehensive product line ranging from cloud platform software to sensors, Acrel offers smart energy meters, power sensors, and protection devices. Their products are widely utilized across industries such as electric power, communications, rail transit, petrochemical, and construction. In 2012, Acrel was listed on the Growth Enterprise Market with the stock code 300286.SZ. The company is committed to delivering innovative and reliable energy management solutions to its global clientele.