LAVT PANELS:
What is an LAVT Panel?
An LAVT panel is a cubicle which houses a Lightning Arrester (Surge Arrester), Surge Capacitor, and Voltage / Potential Transformers for a Phase Isolated Bus Duct.
Lightning arrestor is there to provide protection against any surges in voltage, hence the name lightning arrestor, it is a device that safely diverts any surge in voltage "away" from your plant therefore protecting your equipment against overvoltage conditions.
A capacitor is connected in parallel with the lightning arrester for enhanced protection as well.
The voltage transformer will probably be for either protection purposes or for some instruments on your system.If you have a voltmeter or wattmeter etc on the panel then it is probable that it's supply is derived from the VT. A VT transforms the primary voltage, in this case 11kV down to a low voltage (probably 110V) to give an accurate representation of the system volts, which can be incorporated into protection devices and measuring devices.
LAVT Panels are used in all high voltage power Plants wherein for protection of the Alternator. This unit is phase isolated and is mostly connected to the bus duct.
STARTING RESISTORS
A starting resistor limits the starting torque and current drawn by the motor initially. Once the motor is to speed, the resistor is not needed and is cut out from the circuit.
STARTING RESISTORS are necessary since the dc resistance of a motor armature is very low.Excessive current will flow when dc voltage is first applied unless current is limited in some way. Addingresistance in series with the armature windings reduces initial current. It may then be removed aftercounter EMF has been built up.
WHAT IS A NEUTRAL GROUNDING RESISTOR / NEUTRAL EARTHING RESISTOR?
Ampcontrol Equipments designs and manufacturers Neutral Grounding Resistors for voltage levels upto 36kV for any current rating.
Resistors are manufactured in punched, Rod formed, Wire Wound and Cast Iron form as desired by the customer.
Advantages of using anNGR: -
- Installation of NGR in the system reduces mechanical stresses in circuits and equipment subjected to fault currents. This also reduces the electrical-shock hazards to personnel caused by stray ground fault currents in the ground return path.
- Reduction in the momentary line-voltage dip occasioned by the occurrence and clearing of a ground fault.
- To secure control of transient over-voltages while at the same timeavoiding the shutdown of a facility circuit on the occurrence of the first groundfault.