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Home / Technical Articles / Be smart and cautious when operating an unknown energized low voltage switchgear

Practical experience, dos and don’ts

Switchgear is an integral part of the electrical protection system, which is used for isolating the faulty parts as well as de-energizing the downstream equipment during maintenance or any other usages. “Energized” is the term that signifies that the component is connected to a voltage source or electrically charged with higher potential than earth reference.

Be smart and cautious when operating an unknown energized low voltage switchgear
Be smart and cautious when operating an unknown energized low voltage switchgear

While the most of maintenance and repair works of electrical components are carried out by de-energizing them, some require the operators and engineers to work without interrupting the downstream power supply. It might get a little trickier when the focus is on the switchgear itself.

This article narrates some practical experiences of the author along with dos and don’ts in operating energized LV switchgear during various maintenance and regular functionalities.

While the major point is almost always about safety measures, this article focuses on various other aspects associated with the operation of energized LV switchgear in a real-world example.

Table of Contents:

  1. What does LV switchgear operation mean practically?
  2. Balancing the safety and power interruptions
  3. Practically dealing with unknown LV switchgear assembly
    1. Training, tools, and practical experience
    2. Studying the SLD, equipment placement, and downstream loads
    3. Significance of Standard operating procedure
    4. Advice about maintenance and spare parts
    5. Safety practices
    6. Provision of work assessment and jurisdiction
    7. Preparedness for emergencies

1. What does LV switchgear operation mean practically?

Before diving into the precautionary measures of operation, let’s first define the territory of low-voltage switchgear operation. Isolating the faulty parts and de-energizing the downstream whenever required summarize the major operation territory of any low-voltage switchgear.

Breaking further down, it might include simple trip-close operation, racking the breakers in/out, and other general maintenance activities.

During the normal condition, the downstream loads and appliances should get the uninterrupted power supply and during any abnormal condition or faults, the switchgear must isolate the faulty section by opening the breakers automatically.

Since single switchgear is associated with control of power flow over a wide range of downstream appliances and usages, it is extremely important to ensure that the switchgear is operated by well-trained and capable technicians or engineers only.

In some applications, the uninterrupted power supply is critically mandatory, which requires the technicians to complete the maintenance works without de-energizing.

Figure 1 – Principle sectional view of a low voltage switchgear

Principle sectional view of a low voltage switchgear
Figure 1 – Principle sectional view of a low voltage switchgear with the position of circuit breaker

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2. Balancing the safety and power interruptions

Often, a good deal of electrical equipment, lines, and the system is maintained or repaired while energized because the requirement of downstream loads makes it rather impossible to de-energize the system that leads to a power outage. Barring some works like the splicing of cables, changing the busbar, inspecting the internal configuration of switchgear, etc which require mandatory de-energizing of the system, most of the electric works can be done safely while energized using special safety measures and equipment.

One such illustration is in Figure 2, which requires de-energizing of low-voltage switchgear mandatorily. Testing, calibration, and setting adjustment of switchgear, control equipment, and measurement devices require the operator to work in an energized state.

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Bishal Lamichhane

Electrical Engineer (B.E Electrical, M. Sc Engineering) with specialization in energy systems planning. Actively involved in design and supervision of LV/MV substations, power supply augmentations and electrification for utilities and bulk consumers like airports and commercial entities. An enthusiast and scholar of power systems analysis.

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