According to CIGRE A2.34, the dynamic resistance measurement or DRM (OFFLINE) is a test that offers diagnostics for several diverter or selector switch malfunctions such as: contact problems, broken springs, broken transition resistors, poor contact pressure, inadequate transition time, momentary open circuit, and synchronism motion issues.
Zensol’s DRM principle
Tap windings are powered with a DC voltage source. The current fluctuations are recorded during the switching process. The schematic below shows the principle of the dynamic resistance measurement.
“The TAP-4-PLUS with TAP-DRM accessory can perform dynamic resistance, vibration recordings, and motor current at the same time.”
Read full article in the Reliable Power Testing Special Edition 2021
Zensol advertisement in the issue:
“Zensol TAP-4-PLUS. The newest instrument for OLTC testing”
