Description

The Bender RCM475LY-13 is a high-performance, multi-frequency residual current monitor (RCM) designed for continuous insulation monitoring in complex electrical installations that include power electronic converters, variable speed drives, switch-mode power supplies, or DC components—such as electric vehicle (EV) charging infrastructure, photovoltaic (PV) systems, uninterruptible power supplies (UPS), and medical IT networks. Unlike conventional Type A or F residual current devices (RCDs), the RCM475LY-13 complies with Type B requirements per IEC 62955 and IEC 60755, enabling it to detect all forms of residual current: pure AC, pulsating DC, smooth DC (up to 6 kHz), and composite waveforms.

Housed in a compact 22.5 mm wide DIN-rail enclosure, the RCM475LY-13 continuously measures leakage current via an external toroidal current transformer (CT) and triggers a configurable alarm or control signal when preset thresholds are exceeded. It features a wide adjustable trip range from 6 mA to 30 A, making it suitable for both life-safety applications (e.g., 6–30 mA for shock protection) and fire-prevention scenarios (e.g., 300 mA–30 A for thermal risk mitigation). The device includes a potential-free relay output for local signaling and a Modbus RTU (RS-485) interface for integration into building management systems (BMS), SCADA, or energy monitoring platforms—enabling predictive maintenance through trend analysis of insulation resistance degradation.

Engineered by Bender, the global leader in electrical safety and insulation monitoring, the RCM475LY-13 combines German precision with industrial robustness, operating reliably from -25°C to +55°C and supporting supply voltages of 24–230 V AC/DC. Its self-test function and LED status indicators ensure operational transparency, while its immunity to electromagnetic interference (EMC Level 4) guarantees stability in electrically noisy environments like data centers or industrial plants.

Technical Specifications

Main Features and Advantages

Universal Type B detection for modern power systems: The RCM475LY-13 addresses a critical gap in electrical safety: traditional RCDs cannot detect smooth DC leakage from sources like EV chargers or solar inverters, which can cause dangerous neutral-to-earth voltage buildup or fire hazards. By monitoring all current types—including pure DC—the RCM475LY-13 ensures comprehensive protection in installations with non-sinusoidal loads.

Flexible integration and remote diagnostics: With its built-in Modbus RTU interface, the RCM475LY-13 transmits real-time residual current values, alarm status, and device health to central controllers. This enables early warning of insulation deterioration (e.g., cable aging in underground EV parking), reducing unplanned outages and supporting condition-based maintenance strategies.

Simple configuration without software: Trip thresholds and response behavior (alarm vs. delayed trip) are set via DIP switches on the front panel—no PC or configuration tool required. This simplifies commissioning and reduces training needs for electricians, while still offering professional-grade adjustability.

Robust design for demanding environments: The RCM475LY-13 features galvanic isolation between power, sensor, and output circuits, along with high EMC immunity (IEC 61000-4-4/5). Its wide supply voltage range allows operation in unstable grids or backup-powered systems, and the compact footprint conserves valuable panel space in retrofit projects.

Application Field

In electric vehicle charging parks, the RCM475LY-13 is mandated by standards like IEC 61851-1 Annex D to protect against DC fault currents that could render standard RCDs ineffective. It monitors each charging point or group feeder, triggering disconnection before hazardous touch voltages develop.

In data centers and server rooms, the device safeguards sensitive IT loads by detecting leakage from hundreds of switch-mode power supplies. Early detection of rising ground currents helps prevent server crashes or fire risks in cable trays—critical for Tier III/IV uptime requirements.

In medical facilities, particularly operating rooms using isolated power systems (IT systems), the RCM475LY-13 complements insulation monitoring devices (IMDs) by providing secondary protection against earth faults in non-medical circuits (e.g., lighting, HVAC).

In industrial automation and renewable energy, the RCM475LY-13 protects frequency inverters, battery storage systems, and DC microgrids—environments where harmonics and DC offsets challenge conventional protection. Across all these sectors, the RCM475LY-13 delivers future-proof, code-compliant safety for the electrified world.

Related Products

• RCM420-D: Basic Type A/B RCM without communication; cost-effective for simple alarms

• ISOMETER® iso685: Insulation monitoring device (IMD) for IT systems; used alongside RCMs in medical applications

• AGH420: 42 mm aperture toroidal sensor for conductors up to 35 mm²; commonly paired with RCM475LY-13

• RCM Analyzer: Handheld test instrument for validating RCM performance during commissioning

• EMD475: Earth leakage current detector with analog output; alternative for analog control systems

• RCM490: Higher-end model with Ethernet, web server, and multiple relay outputs

• VIGILANT System: Bender’s full arc-fault and leakage monitoring ecosystem for critical infrastructure

Installation and Maintenance

Pre-installation preparation: Select a compatible toroidal CT (e.g., AGH series) sized for the conductor bundle. Ensure all phase and neutral conductors pass through the toroid—do not include the protective earth (PE). Mount the RCM475LY-13 on a DIN rail away from high-current busbars to avoid magnetic interference. Verify that the supply voltage matches site conditions (24–230 V AC/DC).

Maintenance recommendations: Perform a functional test annually using the built-in test button or an external RCM tester. Inspect wiring terminals for corrosion or loosening, especially in humid environments. Monitor Modbus data trends: a gradual increase in baseline leakage may indicate insulation degradation requiring investigation. Replace the unit if self-test fails or relay contacts show signs of welding.