Description

The BENDER RCMA470LY-21 (order number B94042008) is a high-performance residual current monitoring (RCM) device designed for continuous insulation integrity surveillance in AC, DC, and mixed AC/DC electrical systems. As part of BENDER’s renowned RCM series, this 6-channel monitor detects even the smallest ground leakage currents—from 0.1 mA to 10 A—including pure DC, pulsating DC, and AC components, making it ideal for modern power architectures like EV charging stations, data centers, medical IT systems, solar inverters, and industrial automation.

Unlike traditional earth leakage relays that only respond at trip levels, the RCMA470LY-21 provides early warning of insulation degradation—enabling predictive maintenance and preventing fire hazards, equipment damage, or unplanned downtime.

Application Scenarios

At a Tier III data center in Germany, intermittent server reboots were traced to undetected DC leakage from aging rectifier modules in the 48V backup system. After installing the BENDER RCMA470LY-21. engineers monitored all six critical DC bus segments in real time. The device flagged a rising 12 mA smooth DC leakage on Bus 3—weeks before a thermal event could occur. The faulty UPS module was replaced during scheduled maintenance, avoiding a potential $ 2M+ outage. In this mission-critical environment, the B94042008 wasn’t just a monitor—it was a silent guardian of digital continuity.

Parameter

表格

Note: “LY-21” suffix indicates version with LCD display and Modbus RTU communication. Other variants exist without display or with different output configurations.

Technical Principles and Innovative Values

Innovation Point 1: True Type B Sensitivity for Modern Power Electronics

The RCMA470LY-21 uses advanced fluxgate and differential current transformer technology to detect smooth DC leakage—a growing risk in systems with switch-mode power supplies, VFDs, and EV chargers where traditional Type AC RCDs are blind.

Innovation Point 2: Per-Channel Programmability & Diagnostics

Each of the 6 channels can be independently configured for alarm level (e.g., 30 mA warning, 300 mA trip), response delay, and signal type—enabling tailored protection for mixed-load panels.

Innovation Point 3: Integrated Communication & Event Logging

Via Modbus RTU, real-time residual current values and alarm states are streamed to SCADA, BMS, or cloud platforms. The internal log stores up to 100 events with timestamps—critical for root-cause analysis.

Innovation Point 4: Built-In Self-Test & Compliance Verification

A front-panel “Test” button simulates fault conditions to validate relay and sensor functionality—supporting compliance with NFPA 70B and ISO 55001 asset management standards.

Application Cases and Industry Value

In a U.S. hospital’s isolated power system (IPS) for operating rooms, the RCMA470LY-21 replaced outdated single-channel monitors. Its ability to distinguish between harmless capacitive leakage and dangerous fault currents reduced nuisance alarms by 90%, while ensuring patient safety per IEC 60364-7-710. Facility managers now receive weekly insulation health reports via BMS integration.

Similarly, a Chinese EV fast-charging network deployed the B94042008 across 200+ stations. The device’s DC sensitivity detected failing onboard chargers in connected vehicles—triggering automatic session termination before thermal runaway could occur—enhancing both safety and brand reputation.

Related Product Combination Solutions

BENDER ISOMETER® iso685: Insulation monitoring device (IMD) for IT systems—complements RCM in medical/industrial IT networks

BENDER ANS 425: Current transformers for high-current RCM applications (>10 A)

BENDER EDS440: Ground fault locator for pinpointing insulation faults in complex circuits

BENDER RCMS490: Central evaluation unit for multi-device RCM networks (up to 64 channels)

BENDER Power Supply Units (e.g., MINISG): Stable 24V DC source for RCM reliability

Modbus Gateway (e.g., HMS Anybus): Enables integration into Ethernet/IP or PROFINET networks

BENDER Configuration Software (RCM-Config): PC tool for advanced setup, logging, and firmware updates

Installation, Maintenance, and Full-Cycle Support

Installing the BENDER RCMA470LY-21 requires mounting on a DIN rail, connecting phase/neutral (or DC+) conductors through its internal current sensors (or external CTs for high current), and wiring relay/Modbus outputs. No calibration is needed—the device auto-ranges and self-tests on power-up.

Maintenance is minimal: periodic verification using the built-in test function and firmware updates via Modbus or service port. The LCD provides instant status—no external tools required for basic diagnostics.

We supply genuine BENDER RCMA470LY-21 (B94042008) units with full factory documentation, functional validation using calibrated leakage simulators, and a 24-month warranty. Every device is tested for Type B response, relay timing, and communication integrity. Our technical team offers application engineering support for EV infrastructure, healthcare, and industrial safety compliance.

Contact us for a customized solution—whether you’re designing a new critical power system, upgrading legacy ground fault protection, or securing spares for your BENDER RCMA470LY-21 installations. With over 70 years of electrical safety leadership, BENDER doesn’t just detect faults—it prevents disasters.