What is racking?
Racking is an industry term used to describe the act of connecting or disconnecting a circuit breaker from the electrical bus inside switchgear or a cubicle. A withdrawable circuit breaker can be either racked to (i.e. moved) to a “connect” position or racked to a “disconnect” position.
While there are many different types of circuit breakers used across different voltage classifications, the primary function of racking is to physically connect or disconnect the breaker from the electrical bus. When racked to the disconnected position, a physical air gap is created between the circuit breaker and the electrical bus, allowing the circuit to be isolated for maintenance or service.
What is remote racking?
Remote racking is an industry term used to describe a mechanical or electromechanical system that allows an operator to move a withdrawable circuit breaker between connected and disconnected positions from a remote location. Traditionally, racking a circuit breaker was performed by an operator by directly hand cranking or levering a breaker onto or off an electrical bus while standing in front of the circuit breaker.
Because of the potential for an arc flash incident, remote racking systems allow operators to increase their distance from the circuit breaker during the racking process.
What does racking a circuit breaker mean?
Racking a circuit breaker is the act of physically moving a circuit breaker onto or off an electrical bus, thereby connecting or disconnecting it from an electrical circuit. The circuit breaker may be moved vertically or horizontally, usually by turning a hand-cranked screw or lever.
Who needs to rack a breaker?
Utility, industrial, commercial and petrochemical workers may need to rack circuit breakers to safely perform maintenance or repairs on electrical systems. Power plant operators, mining operations, dams, shipping yards and other facilities may need to de-energize electrical circuits so a circuit or circuit breaker can be safely serviced. Only trained and qualified personnel should rack circuit breakers.
What is a safe distance to be from a breaker when racking?
Safe working distances are required to be established by employers, owners and operators of the electrical equipment, based on the amount of available energy present at the breaker and the electrical system connected to it. Arc flash calculations are required to be performed in order to establish what these safe working distances and limits are for employees and contractors.
Safe working distances can vary significantly depending on the equipment and potential incident energy. Remote racking allows operators to increase their distance from the circuit breaker and avoid standing directly in front of the equipment during the racking process. Safe-T-Rack systems can be operated from distances of up to 150 feet when the application requires it.
Why remote racking?
Remote racking equipment allows operators to increase their distance from a circuit breaker while it is being racked. Increasing that distance can reduce an operator’s exposure to the effects of an arc flash and helps maintain the established safe working distance throughout the racking process.
What is remote racking for?
Remote racking allows an operator to connect or disconnect a circuit breaker from an electrical bus while increasing the operator’s distance from the equipment during the racking process.
What is local vs. remote operation of a circuit breaker?
Local operation of a circuit breaker means operating it at the physical location of the equipment. Local controls are typically located on the switchgear cubicle door or on the circuit breaker itself. Remote operation allows the circuit breaker to be operated from another location, such as a control room or operations center.
How safe is remote racking?
Remote racking can help reduce an operator’s exposure to arc flash hazards by increasing the distance between the operator and the circuit breaker during the racking process. Proper PPE, established safe working distances and all required safety procedures should still be followed when using remote racking equipment.
What is an arc flash?
An arc flash is an explosive release of energy that occurs when electrical current flows through an ionized path in the air. This can happen when electrical current travels between conductors or from a conductor to ground. An arc flash can cause serious injury to anyone in the surrounding area.
How does a circuit breaker cause an arc flash?
When racking a circuit breaker into position, an arc flash could occur because of a mechanical failure or misalignment inside of the equipment when it is being connected or disconnected from an electrical bus.
Potential failures can occur at the circuit breaker or switchgear primary disconnecting stabs or fingers if they are damaged or misaligned during connection or removal from the electrical bus. Other possible causes include insulation failure, mechanical failure or foreign material that creates a short circuit. Racking a circuit breaker under improper operating conditions can also increase the risk of an arc flash.