What is a Ground Fault?

Ground faults occur when current accidentally flows from an energized conductor to the ground, which can inadvertently energize other equipment and potentially cause harm if touched. This occurs when an energized wire comes into contact with the ground part of a junction box or other appliance or device.

Electricity always finds a path to the ground, but in the case of a ground fault, the electricity flows through an unintended path such as a human, animal or equipment.

A ground fault is similar to a short circuit (phase to phase faults) in that large amounts of current are forced through a fuse or circuit breaker which causes the fuse to blow or a circuit breaker to trip. Phase to phase faults happen when an electric flow strays outside its intended circuit, causing the circuit breaker to trip, stopping all current flow. This typical occurs when a hot wire comes loose and into contact with a neutral wire.

Ground faults are much more common than phase to phase (short circuit) faults.

Ground Fault Detection

Ground faults can be costly if not checked. They can cause a fire to erupt, create equipment damage, or even shock or electrocute people and animals. Numerous safety regulations and electrical codes exist to prevent and protect against ground faults.

Thus, ground fault detection is necessary from a business perspective, as a determination from OSHA could find your organization negligent in performing basic preventative maintenance which could lead to a fine, closure and a hurtful negative reputation within the industry.

Along with Ground Fault Circuit Interrupters, Ground Fault Sensors provide the protection you need against ground faults.

What is the Purpose of Grounding?

To eliminate the hazardous shock potential of the ground or floor someone is standing on, electrical enclosures should be grounded. A grounded power system provides a low resistance path for the fault current to flow back to the source without providing a high voltage to the floor or equipment frame.

Almost all electrical enclosures are bonded or grounded, in an attempt to eliminate a hazardous potential that could exist on the device relative to the ground or floor that someone may be standing on. In other words, it reduces shock hazards. When we look at a grounded power system, we want to ensure that there is a low resistance grounding path from grounded devices back to the power source. This ensures that if there is a ground fault from an energized conductor to the frame of a piece of equipment, there is a low-resistance path for that fault current to flow back to the source. If the path became high resistance, the frame of the equipment could have a high voltage on it.

What is a Ground Fault Sensor?

Ground fault sensors consist of a single magnetically permeable toroid surrounding current carrying conductors connected to an electrical device such as a motor, heater element, pump, or other machinery. The current transformer detects any imbalance through the conductors measuring current leakage to ground. The ground fault sensor may then trigger a contactor to disconnect power or to send an alarm to a higher-level control that initiates the appropriate action. Ground fault sensors may be installed at a main breaker to protect the branch circuit or at individual machine feeds to protect equipment. The installed sensors provide an output that can operate a circuit interruption device (like a shunt trip breaker) or feed into an alarm system. By interrupting the current or by alerting an operator, personnel and equipment can be protected.

Ground Fault Monitoring Applications

The ability to precisely monitor ground fault leakage allows the operator to make determinations on how to handle any ground fault conditions. In applications where deterioration over time is expected, the monitoring of ground leakage levels can determine specific maintenance or replacement needs and prevent costly unexpected equipment failure and shutdowns.

There are numerous applications where leakage to ground can exceed 30 mA, yet be safe from causing harm. In some circumstances disconnecting power prematurely may cause significant machine or process damage.

Environmental conditions may elevate leakage, such as excessively humid or wet conditions caused by washdown. Some motor types will have minor flaws in the insulation system, which over time may degrade – increasing ground fault leakage.

Why Choose NK Technologies as Your Supplier

With over 1300 different product designs, NK Technologies continues to be a leader in current sensing technologies in the industrial and automation markets. The San Jose, CA based team is available to help solve your ground fault detection needs with reliable and innovative solutions. NK Technologies stand behind their products with an industry leading 5 year warranty.

What NK Technologies Products Address Ground Faults?

NK Technologies supplies a variety of current sensing components including a line of ground fault sensor products to address various application needs. Available ground fault sensors can provide monitoring of ground leakage current, sensors with fixed setpoints, and sensors that enable adjustable setpoints and delays.