Which type of transformer work requires a voltage sensing device?

The installation of a voltage sensing device is crucial during repair work inside a transformer. This is because such devices are used to monitor and detect voltage levels, ensuring both safety and accuracy while repairs are being conducted. When working on transformers, it is essential to have real-time data on voltage levels to prevent electrical shock hazards and equipment damage.

In comparison, routine maintenance may not require constant voltage monitoring, as it often involves tasks like cleaning or checking connections that do not necessitate direct interaction with live parts. The installation of new transformers usually involves adhering to specific guidelines and does not focus on internal repairs. Testing transformer performance is oriented toward assessing efficiency and performance parameters rather than direct repair tasks. Therefore, having a voltage sensing device is most pertinent to the context of conducting repairs safely and effectively, which is why that option is the correct choice.