Safe Electrical Panel Measurements with a Measurement Window

The need to measure three-phase electrical systems has become increasingly important, especially for simple energy surveys, more complex power quality troubleshooting, or overall electrical performance studies on individual electrical equipment such as transformers and motors.

However, taking three-phase measurements can be dangerous as you need to open electrical panels and put on proper personal protective equipment (PPE). The top risks can carry severe penalties, whether it's personal injury or the need to replace damaged equipment, which in turn leads to the cost of plant downtime. The risks of working inside electrical panels are three-fold:

  1. Arc flash that may cause severe damage to personnel and equipment
  2. Electrocution
  3. Disruption to the operating of the equipment
PQ 400

Balancing the risks with the need to get the data is difficult. As safety requirements and standards continue to improve it often becomes more time consuming to don proper PPE, open the electrical panel, and make the necessary measurements. But it's also critical to collect data so management can make informed decisions and shorten troubleshooting time. The most logical way to make these measurements while mitigating the risk is to leave the electrical panel closed when making the measurement. To improve electrical panel safety and avoid the risk of arc flash, electrocution, and downtime, install an electrical measurement window.

Compliance without compromise. Safety without sacrifice.

An electrical measurement window, like the PQ400, allows users to measure the voltage and current safely without the normal, associated risks. It does this by creating a connection for voltage and current through the cabinet door. For voltage, the live conductors are terminated at the permanently connected window, which is installed on the outside of the electrical panel.

Similarly, suitable current sensors are permanently installed and the signal from those sensors is available on the sockets of the PQ400. This method then complies with safety standards and allows access whenever it’s needed, without needing to open the cabinet.

How does an electrical measurement window work?


To install a measurement window on your electrical panel, you use a standard step drill bit and electro-hydraulic hole punch (114.3 mm, 4.5-inch hole diameter) through the cabinet door. The PQ400 is permanently installed here and allows users to make three-phase voltage, current, and ground connections covering most measurement configurations. Once installed, users can simply:

  1. Unlock the window cover,
  2. Lift the lid, and
  3. Connect the voltage leads of the logger or analyzer.
  4. Connect the leads for the current sensors
  5. Start making critical measurements.

After you’ve taken the measurements, simply remove the voltage and current connections from the front panel interface and lock the window lid, leaving the internal connections in place for future use.

The PQ400 is optimized for the connection of Fluke 173X Power and Energy Logger and 174X Power Quality Loggers. However, there are a range of adapters that make it possible to connect equipment from many manufacturers. The purpose of an electrical measurement window is to enable you to make safe, effective measurements whenever you need to with whatever equipment you have.

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