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Ground Fault Protection Relays

Voltage Indicator Alarm (VIA) provides visual indication and alarm for ungrounded distribution systems.

The VIA has been designed specifically for Ground Fault Indication on Wye or Delta-connected, three-phase, three-wire, resistance grounded or ungrounded power systems. It may be used on systems between 120 volts or 600 volts (up to 690 without CSA approval) or up to any voltage with the use of 120 volts or 240 volts potential transformers (PT’s). Additionally, the VIA can detect DC ground faults on Variable Frequency Drives that are on AC fed systems. One or more optional flush mounted external displays (VIA -R) can be mounted on panel doors or other locations. Isolation inside the VIA protects the external displays from high voltages.

Benefits of VIA

  • Ensure service continuity
  • Suitable for any production plant
  • Ground Fault Indication on Wye or Delta-connected, three-phase, three wire, resistance grounded or ungrounded power systems
  • It does not require any external hardware (each phase is fused inside the VIA enclosure)
  • The VIA can be used on higher system voltages with the use of potential transformers.

CSA and CE approved

Sentri – Ground fault relays from 10mA to 1200A with Zone Selective Instantaneous Protection (ZSIP) for use on solidly grounded and resistance grounded distribution systems.

Arc flash hazard is the energy released in an arc flash and is proportional to the duration of the arcing fault; hence arc flash hazard can be reduced by lowering time delay settings of the ground fault overcurrent protective devices.

Continuity of service is very important, and is maximized by time-current coordination of the ground fault devices. The drawback of time-current coordination is that an extra time delay is required on upstream protection devices.

Zone Selective Instantaneous Protection (ZSIP), improves arc flash safety upstream in the distribution system without affecting service continuity.

With ZSIP, the Sentri relay senses a fault and trips with no intentional delay unless it receives a restraint signal from the Sentri relay immediately downstream; if so restrained, the Sentri relay waits to time out before tripping allowing the downstream Sentri to clear the fault

mGard – ground fault protection for motors and motor control centers from 10mAmps with optional communication and display module for control of 50 individual relays.

The I-GARD mGARD is a microprocessor based ground fault relay designed and built to be used on solidly grounded or resistance grounded systems. This innovative digital electronic relay measures ground fault current using built-in zero sequence current sensor (ZSCS). The mGARD operates on any control voltage from 40-240 volts direct current (DC) or alternating current (AC), and contains an isolated power supply. Options are available for operation at 5 VDC, 12 VDC and 24 VDC.

The mGARD reacts to alternating current only and will reject direct current signals. With the harmonic filtering feature enabled, the mGARD rejects all higher frequencies than fundamental. This can be used to eliminate false tripping when the relay is used on systems with variable frequency drives. With the harmonic filter disabled, the relay will respond to AC currents between 25 and 400Hz. The relay can be connected to the mGARD-SYM remote indicator (with Modbus connectivity) for remote test/reset and monitoring. The mGARD-SYM provides detailed device status information.

Benefits of the mGARD:

  • Due to its very low sensitivity (down to 10ma) the mGARD is ideal for people safety in areas wherever the public is exposed to water and electricity such as water parks and fountains.
  • Ideal for Motor Control Centers
  • Suitable for solidly grounded or resistance grounded systems, three phase or single phase loads.
  • Wide range of trip levels and delays

Wide range AC and/or DC control voltage

GCHK-100 – a ground fault relay for trailing cables for use on systems up to 4160V and with advanced touch voltage protection.

Operator safety from electrical shock depends to a large extent on the integrity of the grounding of the equipment when it is energized. It is vital, therefore to know if this grounding has been compromised; to do this a second auxiliary ground conductor is incorporated in the trailing cable to the mobile equipment.

The GCHK-100 monitors the loop resistance of the two grounds and trips when it exceeds a preset value.

Additionally, the relay will detect if the ground loop has become shorted or has opened. In the event of a ground connection failure and internal leakage within the mobile equipment, it is possible for the frame of the equipment to become live and present a shock hazard.

For added protection, the GCHK-100 detects high equipment frame voltages and quickly trips the relay. This feature will cause a trip twice as fast as the ground check and five times quicker for frame voltages exceeding 100V.

To service the special needs of the mining industry I-Gard has developed the GCHK-100 ground fault relay to improve safety for personnel and equipment in underground or above ground applications. Detection of ground faults is important where safety from electric shock and fire risk can occur and cause serious equipment and personnel hazards.

The relay is designed for use with resistance grounded systems up to 4160V but could be used with grounded systems in branch circuit applications where Load current is limited to 800A.

SIGMA –A combination NGR monitoring and ground fault relay that protects against ground faults and abnormal conditions in the path between system neutral and ground possibly caused by loose or improper connections, corrosion, foreign objects or missing or compromised ground wires.

A major safety concern is the loss of neutral path, i.e. broken wire from source neutral to resistor or between resistor and ground or even a bad or loose connection.

The result is changing from a high-resistive grounded system to either an ungrounded or solidly grounded system without anyone knowing it! This would cause severe safety hazards, such as transient over-voltages, unlimited fault current, escalating arcing faults etc

With the Sigma monitoring relay the neutral path from neutral to ground (including resistor) is continuously monitored for integrity. If an open or short circuit occurs, the relay will alarm.

The I-Gard SIGMA monitoring relay is a combination neutral grounding resistor (NGR) monitor and ground fault relay. In distribution systems employing resistance grounding the SIGMA monitoring relay protects against ground faults and abnormal conditions in the path between system neutral and ground possibly caused by loose or improper connections, corrosion, foreign objects or missing or compromised ground wires.

The SIGMA monitoring relay measures the current through the NFR, the transformer neutral-to-ground voltage and the NGR resistance. The relay compares the measured values against the field settings of the relay and provides relay outputs and LED indications when an abnormal condition is detected.

DSP OHMNI – The most advanced resistance grounded relay system in the market with protection of up to 50 individual feeders, integral resistor monitoring, main-tie-main protection, unique selective second fault feeder tripping, instantaneous and time delay feeder tripping, MODBUS communication and more.

The original HRG system developed in the 1950’s and 1960’s provided process continuity, however, they were unable to solve potential safety issues, such as a second ground fault, leaving the ground on the system too long and monitoring of the neutral path.

There is a concern that the first ground will be left on the system and ignored. Since the zero-sequence current transformers identify the faulted feeder, the relay has the ability to begin a (user programmable, usually in hours) timer when the ground fault first occurs. Unless the ground fault is removed or the timer is reset, the faulted feeder is shunt-tripped offline. The purpose is to continually remind maintenance personnel to either remove the ground fault or to reset the timer every so many hours.

In the event that a second ground fault occurs prior to removing the first ground fault, a phase-to-ground-to-phase or phase-to-phase fault can occur. When this occurs on the original HRG, it would cause both feeder circuit breakers and possibly the main circuit breaker to trip.

However, the modern relay can be programmed to prevent this and only shunt-trip the lesser priority feeder, leaving the more important feeder on-line.

I-Gard edgewound resistors are designed and built to meet the most demanding mechanical and electrical requirements in the industry.

I-Gard edgewound resistors are designed and built to meet the most demanding mechanical and electrical requirements in the industry today. They are constructed of flat stainless steel electrical alloy, wound on its edge to form a helical resistive element. The element is then mounted on solid porcelain cores. Welded terminals at both ends of the resistor provide the means of connection and termination. I-Gard uses stainless steel rods for mounting the resistor elements. This provides better protection against corrosion and also allows better high-temperature performance of the resistor. It also lowers the inductance of the resistor, improving its voltage surge to withstand capability. I-Gard’s special porcelain cores are designed for through-bolt or flat-bar frame mounting.

Edgewound resistors are available in standard sizes from size 3 (9″ in length), to size 10 (30″ in length). The elements are available in continuous current ratings from 11 amperes to 105 amperes. For more information on ratings and corresponding I-Gard part numbers, see our edgewound ratings table.

I-Gard wirewound resistors are ideal for small horsepower crane control, Y Delta starting and dynamic braking. They are also ideal for high resistance neutral grounding as well as heaters and load banks.

I-Gard’s FDL series wirewound resistors feature corrosion-resistant nichrome wire, helically wound into a long spring-like coil. The construction can be supplied open, or with screen enclosures for personal protection, or louvered-enclosed for both personal and all weather protection, in either NEMA style or IP rated enclosures.

The electrically efficient construction of the FDL element allows the highest possible wattage ratings per linear inch, consistent with NEMA standards of performance. As an added benefit, the same design feature permits high wattage ratings, making this an excellent space heater, both for natural convection and forced air use.

I-Gard wirewound resistors are ideal for small horsepower crane control, Y Delta starting and dynamic braking. They are also ideal for high resistance neutral grounding as well as heaters and load banks.

Available in a range from .5 to 100 ohms and from 1.6 to 27 amps, we’re certain to have the wirewound resistor you’re looking for. For more information on ratings and corresponding I-Gard part numbers, see our FDL Ratings Table.

I-Gard type SSG grid resistors offer more power and greater reliability and flexibility than almost any other grid resistor on the market.

I-Gard type SSG grid resistors offer more power and greater reliability and flexibility than almost any other grid resistor on the market. Ideal for high power applications such as motor starting and dynamic braking of large motors, they are constructed to NEMA standard dimensions for easy replacement of all other major grid manufacturers.

I-Gard’s use of special resistor grade stainless steel means a stable resistance over a wide temperature range, providing predictable performance for end users. The special grade of silicon mica insulation provides tremendous overload capability. IPC Ggrid resistors have been tested at continuous temperatures of up to 700C with no loss of performance or reliability.

NEMA standard dimensions and a handy cross-reference table ensure easy replacement of most manufacturers’ grid resistors.

I-Gard’s SSR Series Resistors are perfect for high horsepower, high voltage motors, as well as large motor-control applications where continuous operation under extreme conditions is common, such as speed regulating and dynamic braking.

I-Gard’s SSR Series Steel Ribbon Resistors feature a 4-inch wide stainless steel element that is folded concertina-style to provide the length required for specific resistance values. Resistor elements are manufactured from high-quality resistor-type stainless steel with a low temperature coefficient of resistance.

I-Gard’s SSR Series Resistors are perfect for high horsepower, high voltage motors, as well as large motor-control applications where continuous operation under extreme conditions is common, such as speed regulating and dynamic braking. Stainless steel end mounting channels and through-bolts are available for highly corrosive environments or prolonged outdoor use. High watts per bank reduces the number of banks required for large Wound Rotor Motor applications such as Phosphate Slurry Pumps, Water and Sewage Pumps, Mine Hoists, Overhead Cranes, and Mill Drives.

Standard ‘Mill Bank’ dimensions, with amps from 200 to 525 and ohms from .035 to .162, interchange easily with all major brands. For more information on ratings and corresponding I-GARD part numbers, see our Ribbon Ratings Table.