Handling of discharge issues in the cable compartment of high-voltage switchgear

High voltage switchgear in the process of using a range of troubles or failings, on these problems we must carefully analyse, make a judgment, and according to the results of the evaluation of the issue will certainly be handled in a timely way. Today, to inform you about an instance  high-voltage switchgear cable television space discharge issue.

1. site scenario

In the summer patrol, 35kV substation KYN61-40.5 kind switchgear can constantly be listened to. In the switchgear cord space, there is a periodic "sizzle" discharge sound. On rainfall or damp days, the sound is much more obvious. In the event of rumbling, the system will immediately experience a power outage, seriously influencing the production and living order.

2. check and evaluate

Make use of the opportunity to quit the maintenance of the switchgear above the part of the one-by-one examination.

( 1) Substation at the very beginning of the circulation space: indoor ordinary temperature of 25-27 ℃, air relative humidity of 75% ~ 85%. The relative humidity of the air inside the cable trench is more than 85%, which is substantially greater than the ordinary interior moisture.

( 2) Feeder line terminals have no apparent traces of discharge, and feeder wire insulation is regular.

( 3) Remove the lightning arrester electrical wiring. Discharge audio still exists, suggesting that the discharge is not in the lightning arrester.

( 4) after the power outage, each breaker handcart one by one out; pull out the I back breaker handcart, "Z" noise becomes smaller. Pull out the I back circuit breaker handcart, "Z" noise disappears. In the breaker handcart column and the back side, plate asked to raise the silicone rubber insulation board and re-run the circuit breaker, the "Z" audio vanished. From this reasoning, the discharge part remains in the backside plate of the breaker column.

3. measures.

( 1) the substation around the drainage ditch to dredge, the cable trench wetness treatment, and in the substation on the ground floor to set up a high-power commercial dehumidification air conditioning. In summer, the interior temperature level of the power distribution space is managed at 23 ± 2 ℃, and in wintertime, the room temperature is regulated at 20 ± 2 ℃. The relative humidity of the air in the distribution area is purely regulated at 40% ~ 50%. Installment of temperature and humidity online tracking gadgets in the circulation room; once the temperature and moisture problems are found, prompt modifications will certainly be made to ensure the risk-free and stable procedure of the switchgear and relay defense tools.

( 2) Boost silicone rubber insulation boards between the breaker cart columns and in between the columns and the back side panels.

( 3) Increase the number of summer inspections in the distribution area equipped with a partial discharge tester and infrared thermal imager.

( 4) In order not to have an air pollution flash accident, consistently on the current transformer, potential transformer, high voltage circuit breaker, lightning arrester, charged screen device and blade switch, and various other tools case, as well as assistance insulators for cleaning and attaching. Heavily contaminated insulators outside the brush are anti-fouling paint.

( 5) Silicone rubber to boost the creepage range skirt than the external insulation of electric tools umbrella by approximately 100 mm in the tools porcelain surface area addition of silicone rubber, to stop the event of device fouling flash.

Anti-fouling flash job is summarised as "climb, move, paint, plus": climb: that is, to readjust the devices leak than distance, making use of anti-fouling insulators or synthetic insulators; sweep: sweeping the surface of the equipment dust; paint: paint RTv paint (paint RTV paint can protect against the water film covering, obstructing the development of the water film, properly decrease the strength of the discharge to minimize the malfunction of the tools) Plus: include the installment of Silicone rubber, raise the creepage range skirt.

Furthermore,  in the substation layout, high voltage electric switchgear ought to be avoided as long as possible on the ground floor of the building.

4. Conclusion.

After following a selection of procedures, our company's substation operation reliability has enhanced dramatically. We have entirely addressed the issue of summertime electrical storms causing power outages.