The Bender ISORW425-D4W-4 is a high-precision insulation monitor designed for ungrounded AC/DC IT systems, including 3(N) AC, AC/DC, or DC 0 configurations. It continuously monitors insulation resistance (R-mode) or impedance (Z-mode) for systems with nominal voltages up to 440V. Its unique separated power supply design enables monitoring even during system power-off, ensuring uninterrupted safety.
Supporting 50/60Hz insulation impedance measurement, the device automatically adapts to system leakage capacitances up to 300μF in R-mode and 1μF in Z-mode, accommodating diverse load conditions. With under/over-voltage detection, it accurately measures RMS system voltage. Compliant with EN 50155 for railway applications, it is ideal for rail transit, industrial control, and harsh environments, providing reliable insulation alerts to safeguard system stability and operational safety.