What is leakage current in surge arrester?
Abstract: Metal-Oxide arresters are used to protect substation’s equipment against surges. Because their constructive properties, a small current, called leakage current, flows through them in normal operation condition.
What is rated voltage of surge arrester?
For a solidly grounded system, the continuous operating voltage is 13,800 divided by the square root of 3, or 7970 V. This is above the MCOV of 7,650 V for an arrester rated 9 kV.
How does a high voltage surge arrester work?
A surge arrester works by diverting the extra voltage into the earth wire, rather than flowing through the electronic devices, while at the same time allowing the normal voltage to continue along its path.
How is the surge arrester connected to protect the transformer?
Surge arresters are installed on a transformer to protect it from over-voltage transients. A surge arrester is connected to each phase conductor just before it enters the transformer. At normal operating voltages, the surge arrester must behave like an insulator, isolating the phase conductor from ground.
How do you detect a surge arrester?
It is desirable to check condition of Surge Arrester at regular time intervals, by measuring the resistive element of the continuous leakage current in service without decreasing energy of Arrester. Reliable measurements achieved by the instruments based on the principle of “Voltage Signal” as a reference.
Why is surge arrester always less than line voltge?
Reason is, arrester is always connected in between line and ground. Line to ground Voltge is always less than line to line voltage during normal system operation. See the table below. Note. Duty cycle voltage is usually equal to the temporary maximum voltage arrester can experiance.
What’s the rating of a 33 kV surge arrestor?
The surge arrestor for 33 kV system is of 30 kV rating, which is well above the phase to ground voltage (across which the surge arrestor is connected). Hope this helps. Let me know if you have any query. What does Google know about me? You may know that Google is tracking you, but most people don’t realize the extent of it.
What happens to the leakage current in an arrester?
Metal Oxide Disks, the heart of an arrester, has a positive temperature coefficient at operating voltages. In other terms, as an MOV disk increases in temperature, its leakage current also increases. Leakage current is current that flows through the disk during steady state operation.
How is the voltage of an arrester rated?
Arrester voltage is rated in terms of the Maximum Continuous Operating Voltage (MCOV) that it will experience based upon the AC system design. If the example above is an ungrounded or delta system, the arrester MCOV must equal or exceed the max system voltage 145kV.