Can The Disconnector Be Operated Under Load?

Disconnect switches must never be operated under load. A disconnect switch is an "isolation" device, not an "operation" device. Simply put, a disconnect switch does not have the ability to interrupt or connect normal load current; forced operation will cause serious accidents.

1. Root Cause:

Lack of an arc-extinguishing device. Structural design determines function; the primary design function of a disconnecting switch is to provide a visible, safe disconnect point in the circuit to isolate the power supply and ensure the safety of maintenance personnel. It lacks a dedicated arc-extinguishing chamber to extinguish the strong arc generated when interrupting current.

2. Direct Consequences of Operation Under Load:

When the circuit is under load, directly disconnecting the disconnecting switch will generate a strong power arc at the moment its moving and stationary contacts separate.

Arc Nature: An electric arc is a high-temperature, highly conductive plasma, with temperatures reaching thousands of degrees Celsius.

Due to the lack of an arc-extinguishing device, this arc will be stretched very long and cannot be extinguished quickly on its own.

3. Serious Hazards Caused:

A continuously burning arc can lead to a series of catastrophic consequences.

Same-phase short circuit:

The stretched arc may spread to adjacent phases, causing a phase-to-phase short circuit and generating a huge short-circuit current.

Short circuit to ground:

The arc may also splash onto the grounded switch cabinet or support, causing a short circuit to ground.

Equipment Damage:

The disconnector itself may be burned. The high-temperature electric arc melts and vaporizes the contact material, causing severe contact damage or even welding.

Adjacent equipment may be damaged. The electrodynamic and thermal effects of the short-circuit current may deform the busbar and cause insulators to burst.

Personal Injury:

The electric arc explosion generates tremendous sound, light, and heat shock, which may cause severe arc burns to operators, even endangering their lives.

System Accident:

The resulting short circuit may cause the upstream circuit breaker to trip, causing local or large-scale power outages and affecting power supply reliability.

The core function of a disconnector is safety isolation, not current interruption. Any operation of a disconnector under load is an extremely dangerous violation and one of the main causes of power accidents. In actual operation, strict electrical and mechanical interlocking devices, as well as standardized operating procedures, must be used to prevent such misoperations.