When conducting live testing of lightning arresters, many engineers have found that there are three measurement options for HZ-20A: wired, wireless, and no PT. Different measurement methods have different wiring, accuracy, and applicable scenarios, and it is easy to encounter problems if they are not clear about them.

Wired measurement method

The voltage signal is introduced from the PT (voltage transformer) secondary end through a test line, and the cable is connected to the 6-core aviation seat of the host. This is the most basic measurement method with the highest accuracy, suitable for situations where PT is available on site for easy wiring.

After setting the PT ratio in the system settings, the instrument can directly display the primary voltage of the busbar without the need for manual conversion, making it convenient for recording and comparison.

Wireless measurement method

The voltage signal is also taken from the PT secondary terminal, but connected to the 6-core aviation seat of the wireless module (randomly attached). The wireless module transmits the voltage data to the host through the wireless signal. The current wiring method is exactly the same as wired measurement.

Suitable occasions: The distance between the host and PT is far, making it inconvenient to connect wires; Or the on-site layout of the substation is complex, and wired cables may pass through multiple intervals, resulting in messy wiring. The wireless method eliminates the signal interference risk caused by long cables, while allowing operators to operate the host at a safer distance.

No PT measurement method

There is neither wired voltage nor wireless module, only collecting current signals. Suitable for situations where there is no available PT or it is inconvenient to draw reference voltage.

It should be noted that in the absence of PT mode, the UI angle (voltage current phase difference) is fixed at 83.5 °, which is an empirical estimate. The calculated resistive current has a certain error and the accuracy is lower than that of wired and wireless modes. Used for rough judgment of lightning arrester status, not suitable for precise analysis or as official testing data.