The ground detector is a device that detects the resistance of conductor insulation to the ground. The insulation strength of an ungrounded distribution system can be determined using an ohmmeter or a sequence of lights. The majority of power distribution systems in use today are grounded, however, some ungrounded systems still exist.
The ground detector is a device that detects the resistance of conductor insulation to the ground. The insulation strength of an ungrounded distribution system can be determined using an ohmmeter or a sequence of lights.
When it’s difficult to establish permanent grounds for equipment, 3 Phase 3 Wire (Ungrounded) systems are employed. Crushers and conveyors in gravel pits and quarry operations, as well as drill rigs in isolated places, are examples of this.
In addition, these systems are employed in procedures that can’t be stopped right away since doing so would be dangerous. endangers people or property A abrupt interruption in pumping or process equipment could result in unsafe pressures or catastrophic collapse.
Consider a crusher in a mining operation that is powered by a 500 horsepower engine. This system is used in a number of operations. When a 3 phase 3 wire encounters its initial ground ungrounded system, the motor will continue to run with no indication that one of the phases has failed. The engine, on the other hand, will be badly damaged if a second phase goes to the ground.
As a result, it’s critical that there’s a signal when a ground happens in the system. The National Electric Code, in fact, mandates it. Visual/Audio ground detectors are made by Erickson Electric (Model XVAP). The entire system is monitored by a single ground detector.
If it’s installed before the main service switch and a ground occurs, opening the main switch will determine whether the ground is on the customer’s or utility’s side. (While the theory is sound in theory, it fails in practice.)
The main switch would never be opened to determine the position in the real world). If a ground occurs in the system, the electrician must isolate components of the electrical system to locate the ground. This is accomplished by turning on each circuit in the distribution system.
Check the panelboard to see if the ground detector indicates that the condition has returned to normal. The voltage is monitored by the ground detector. It is not capable of causing a power surge. A power surge, such as a lightning strike, can harm it.
sed in 3 phase 3 wire (ungrounded) systems where it is difficult to install a Permanent base for equipment. Gravel pit or mine operations and drill rigs in remote areas. These systems are also used in operations that should not be stopped immediately because doing so Endangering personnel or equipment.
This can be in pumping or process equipment. Where a sudden stop may result in dangerous pressure or catastrophic failure.
Let’s take for example a crusher that is driven by a 500 horsepower motor in mining operations that use this system. When the first in a 3 phase 3 wire is ground Underground system motor will continue to work without any indication that there is a phase The base has been created.
If however, the second phase goes to the ground then the motor will be seriously affected damaged. It is therefore of utmost importance to indicate when there is a basis occurs in the system. It is actually required by the National Electric Code. Ericsson Electric manufactures visual/audible ground detectors (Model XVAP).
These ground detectors are available in 120V, 240V, 480V, and 600V. are available for Application. High voltage applications require that potential transformers be used as ground detectors.
THEY ARE FOR USE ON 3 PHASE 3 WIRE UNGROUNDED ONLY systems they are not ground fault devices. They do not obstruct power. The Model XVAP Ground Detector is provided with an internal fuse block.
Protected by fuses installed in the internal fuse block. protect the fuses Conductor to the ground detector and allow the ground detector to be disconnected Should it be removed for repair. (If the ground detector is mounted remotely Source – then separate, customer-supplied fuses should be installed as close to the source as possible).
A ground detector is used to monitor the entire system. If it is installed further Contains the main service switch and ground, opening the main switch would be installed if The land is on the client-side or utility side. (While the theory is good in actuality. The world will never be opened to establish the main switch location). if in the field The system is the electrician should isolate and establish the ground location
Ohm Meter Ground Detector Method
A DC voltage is delivered to the conductor in the ohmmeter method (below Figure). If a leakage path exists between the conductor insulator and the ground, a current proportionate to the conductor’s insulation resistance will flow via the ground to the ohmmeter.
Ground Detector Lamp Method
The ground detector lamp approach (shown below) employs a set of three lamps connected to the system through transformers. The switch is closed to check for grounds, and the brightness of the lamps is observed.
If all of the bulbs are the same brightness, there is no ground and all of the lamps receive the same voltage. If one lamp is dark and the other two are brighter, the period in which the dark lamp is lit is called the dark phase.
GROUNDING METHODS OF MEDIUM-VOLTAGE DISTRIBUTION NETWORKS
The primary objectives of system grounding are to reduce voltage and heat strains on equipment, ensure people safety, reduce communications system interference, and aid in the discovery and eradication of ground problems.
Except for voltage stress, operating a system as ungrounded, high-impedance grounded, or resonant grounded limits ground-fault current magnitudes and meets the majority of the objectives listed above.
These grounding methods have the disadvantage of causing faults. Problems with detection (protection) sensitivity We can design a system grounding that decreases voltage stress but increases fault current magnitudes. However, to avoid thermal stress and communications channel failure in such a system, the defective circuit must be de-energized immediately.
Interference, as well as human safety risks The disadvantage of this system is that service must be provided on a timely basis. Even with temporary failures, the service is disrupted.