Protection against Ground Potential Rise (GPR)
The SensorGuard System was developed by MCT Electronics in the US and is designed to protect electrical/electronic equipment from Ground Potential Rise (GPR) associated with lightning strikes.
What does the SensorGuard system do?
It isolates/disconnects the equipment from the grid during a thunderstorm.
Why is this important?
When the equipment is no longer connected to the AC/grid, then it is also no longer connected to the AC ground and therefore is immune to the GPR during lightning activity.
How is the equipment energized when it is disconnected from the grid?
When the protected equipment is disconnected from the AC, it runs off the batteries of the UPS system it is connected to until the lightning storm has passed.
The SensorGuard system compliments conventional lightning protection. Traditionally, lightning protection focused on the design of a controlled, low impendance discharge path to the ground. There, the lightning induced energy would dissipate through an earthing system comprised of inter-connected ground electrodes. If a grounding system is small, well designed and the soil dissipates charges very quickly, then there is a relatively good chance that GPR following a lightning strike would not cause serious damage to the equipment. The larger the site and the greater the ground resisistivity, the greater the rsik of damage to the equipment because of elevated voltage levels.
How the SensorGuard system works
The SensorGuard system is comprise of three parts: Sensor, Control Module and Contactor. The sensor detects an increase in positive ions associated with thunderstorms and then sends a signal to the Control module. The Control module is connected to the 120 VAC line voltage and is also connected to the relays of the Contactor.
What does the SensorGuard system do?
It isolates/disconnects the equipment from the grid during a thunderstorm.
Why is this important?
When the equipment is no longer connected to the AC/grid, then it is also no longer connected to the AC ground and therefore is immune to the GPR during lightning activity.
How is the equipment energized when it is disconnected from the grid?
When the protected equipment is disconnected from the AC, it runs off the batteries of the UPS system it is connected to until the lightning storm has passed.
The SensorGuard system compliments conventional lightning protection. Traditionally, lightning protection focused on the design of a controlled, low impendance discharge path to the ground. There, the lightning induced energy would dissipate through an earthing system comprised of inter-connected ground electrodes. If a grounding system is small, well designed and the soil dissipates charges very quickly, then there is a relatively good chance that GPR following a lightning strike would not cause serious damage to the equipment. The larger the site and the greater the ground resisistivity, the greater the rsik of damage to the equipment because of elevated voltage levels.
How the SensorGuard system works
The SensorGuard system is comprise of three parts: Sensor, Control Module and Contactor. The sensor detects an increase in positive ions associated with thunderstorms and then sends a signal to the Control module. The Control module is connected to the 120 VAC line voltage and is also connected to the relays of the Contactor.
The output of the Contactor is 120 VAC during the normal system operation. Once the lightning activity is detected, the relays in the Contactor are switched causing the connection to the grid to be interrupted. Since there is now no longer a physical connection between the grid and the equipment, the equipment is now isolated and protected.
A UPS system is also required. Its function is to provide the power back-up for the protected equipment during the time when the equipment is off the grid. Once the thunderstorm has passed by and the Control Module has reset the relays of the Contactor, grid power to the equipment is restored.
A UPS system is also required. Its function is to provide the power back-up for the protected equipment during the time when the equipment is off the grid. Once the thunderstorm has passed by and the Control Module has reset the relays of the Contactor, grid power to the equipment is restored.
Lightning Protection of Communication Sites
Most radio communication sites model their lightning protection based on Motorola's R56 grounding standard, leaving out a critical component: Dealing with GPS proactively. Modern technologies allow manufacturers to build computers, computing equipment and wireless communication systems with integrated chip technologies operating at very low power levels. This in turn has made communication sites more suseptible to transient voltage spikes and the effects of GPR. Changing environmental conditions also strongly influence the soil's conductivity and its ability to absorb lightning
Most radio communication sites model their lightning protection based on Motorola's R56 grounding standard, leaving out a critical component: Dealing with GPS proactively. Modern technologies allow manufacturers to build computers, computing equipment and wireless communication systems with integrated chip technologies operating at very low power levels. This in turn has made communication sites more suseptible to transient voltage spikes and the effects of GPR. Changing environmental conditions also strongly influence the soil's conductivity and its ability to absorb lightning
induced charges. Esspecially during dry and hot periods when the chance of lightning storms are highest, the ground is much drier preventing the lightning induced energy from dissipating quickly. This in turn elevates the ground voltage (GPR) higher and for longer periods of time because of the slower depletion rate. In order to be compliant with the Canada Electric Code, the AC neutral has to be grounded. That means that all transmitters and receivers in a communication shelter are grounded from two sides: Through the shields of the transmission lines at the antenna ports and also through the AC power connection to the grid. During a (near) lightning strike, the ground potential at the antenna ports is most likely at a different potential over the ground potential of the grounded AC line that energizes the equipment. This in turn generates a voltage drop and if very low, will only reduce the life cycle of the equipment and if high, will damage the equipment immediatly. The SensorGuard system prevents this possible grounding loop by isolating the protected equipment electrically from the AC ground. Considering the low cost of a typical SensorGuard system that will switch 120 VAC with a load of up to 30 amperes for only + $1,500.00, one could wonder why the SensorGuard system is not yet standard everywhere.
The SensorGuard system is new technology with different models designed for different applications. Any system that is mission critical should be protected from GPR using SensorGuard. It is ironic that high-speed wireless microwave links are often specified to a have a reliability factor of 99.99995% and yet, we don't pay any attention safeguarding the system's operating voltage. SensorGuard systems are not only designed for the communication industry. Any installation using electrical/electronic equipment that is considered mission critical should be protected against GPR. The larger the site and the drier the ground, the more important protection against Ground Potential Rise becomes.
Please contact us for more information on the SensorGuard system, an assessment of your communication site or identifying site grounding problems you may have.
The SensorGuard system is new technology with different models designed for different applications. Any system that is mission critical should be protected from GPR using SensorGuard. It is ironic that high-speed wireless microwave links are often specified to a have a reliability factor of 99.99995% and yet, we don't pay any attention safeguarding the system's operating voltage. SensorGuard systems are not only designed for the communication industry. Any installation using electrical/electronic equipment that is considered mission critical should be protected against GPR. The larger the site and the drier the ground, the more important protection against Ground Potential Rise becomes.
Please contact us for more information on the SensorGuard system, an assessment of your communication site or identifying site grounding problems you may have.
