SERAD IMD/5

Overview

SERAD IMD/5 is an insulation monitoring device from SERAD, used for continuous insulation resistance supervision on ungrounded IT power systems. SERAD IMD/5 detects insulation degradation between live conductors and protective earth, and triggers alarm output before dangerous earth faults develop. SERAD IMD/5 is widely installed in engine rooms, marine vessels and industrial IT distribution panels, and commonly supplied as spare replacement for low-voltage IT network safety supervision.

Features

SERAD IMD/5 supports continuous measurement of insulation resistance, with adjustable alarm threshold and separate pre-alarm and main alarm relay outputs. It uses the low-frequency measuring injection principle, which works reliably on AC, DC and mixed AC/DC IT systems, and is not easily affected by distributed capacitance of long cables. SERAD IMD/5 has a front display and LED indicators to show real-time insulation resistance value, alarm status and device fault. It includes built-in self-test function for regular verification of measuring circuit integrity, and can be equipped with Modbus communication option to transmit resistance values and fault status to PLC, DCS or monitoring SCADA. SERAD IMD/5 has continuous internal diagnostics for power supply failure and measurement circuit error, and meets marine and industrial EMC requirements.

Specs

SERAD IMD/5 is designed for IT isolated power networks. The applicable system voltage range, measuring range and alarm settings are configurable via front keys or software. Relay outputs are potential-free contacts for remote alarm and SOE logging. It requires auxiliary supply according to the variant code, and the measuring method avoids interference with normal power loads. SERAD IMD/5 is widely supplied as exchange spare for marine engine panels and industrial IT distribution cabinet maintenance.

Principle

SERAD IMD/5 injects a low-amplitude test signal into the ungrounded IT system. The return signal is sampled and calculated to derive the insulation resistance between the network and earth. When insulation resistance falls below the set threshold, the internal logic activates the alarm relay. The measured insulation value and fault flags from SERAD IMD/5 can be sent to the supervision system. If the measuring circuit is damaged or the self-test fails, the unit raises a device fault alarm to remind maintenance personnel. It does not trip the power supply automatically; it gives early warning so that earth fault search and repair can be carried out without shutting down critical loads.

Applications

SERAD IMD/5 is used for marine vessel engine room IT systems, medical isolated power supplies, offshore skids and industrial auxiliary ungrounded distribution networks. It protects pumps, navigation equipment, emergency loads and safety-related circuits from single earth faults that can develop into short circuits. SERAD IMD/5 is selected for spare inventory, panel retrofit and insulation monitoring system upgrade projects. It is the core monitoring device for safety supervision of isolated IT power systems.