At substations, distribution rooms, or cable maintenance sites, technicians often need to measure the insulation resistance of equipment such as transformers, instrument transformers, and circuit breakers. Different equipment has different rated voltage levels. If only a single-voltage-range insulation resistance tester is available, multiple instruments often need to be carried, increasing the on-site burden. In addition, factors such as on-site electromagnetic interference and humidity changes can also affect the stability of measurement results. To address the above scenarios, the DRD-50C digital insulation resistance tester provides multiple voltage outputs and a relatively wide measurement range, making it easier for technical engineers to complete insulation resistance measurements under various working conditions.
The instrument provides two voltage output combinations: one with four selectable ranges of 250V, 500V, 2500V, and 5000V, and the other with two selectable ranges of 5000V and 10000V. Users can select the corresponding range according to the rated voltage of the equipment under test, avoiding measurement deviation caused by voltage mismatch. The resistance measurement range is 0–400GΩ, covering common insulation testing needs from low-voltage motors to high-voltage power equipment.
The instrument panel is equipped with a green LED indicator. When the green LED lights up, it indicates that the current measurement value is in the high range interval, and the insulation resistance value should be read on the outer ring. This design helps operators quickly locate the reading area when observing under strong light or from a distance, reducing the possibility of misreading. The display section adopts a combination of digital and scale markings, balancing intuitiveness and precision.
Fixed-range insulation resistance testers usually output only a single voltage, such as 2500V or 5000V, and are suitable for repetitive testing at a specific voltage level. In contrast, the multi-range design of the DRD-50C allows a single instrument to cover multiple voltage levels, reducing the number of devices that need to be carried. For maintenance teams that need to test both low-voltage control circuits and high-voltage main equipment, this flexibility can shorten preparation time. On the other hand, the operation panel of a multi-range instrument is relatively complex, requiring operators to be familiar with the range and wiring method corresponding to each setting to avoid measurement errors caused by selecting the wrong range. When choosing, technical engineers should weigh the voltage distribution of the equipment under test in daily work and the testing frequency.
The DRD-50C is suitable for power system maintenance, electrical equipment maintenance in industrial and mining enterprises, and insulation inspection after cable laying. Measurement targets include power transformers, voltage transformers, current transformers, high-voltage switches, power cables, and surge arresters. When used in high-humidity environments, it is recommended to use shielded terminal wiring to reduce the impact of surface leakage current on measurement results.
