Views: 187 Author: Site Editor Publish Time: 2021-05-04 Origin: Site
The construction of automated distribution network is inseparable from the fault indicator. In this article, we will take the overhead fault indicator as an example to show you the installation of fault circuit indicators.
Choose the installation location according to the line distance and topography to achieve practical and convenient effects. For the 10KV main line, a set of tensile poles of about 2km or the previous base pole with circuit breakers should be installed to facilitate disconnection in case of failure. Generally, the main line should be installed with three groups of cable fault indicators. In addition, we should consider the pole tower with convenient transportation to facilitate observation in case of failure. When there is a fault, the line fault indicator installed between the fault point and the power supply will show a red mark, and line patrol personnel can correctly determine the faulty line section according to the display of each fault indicator.
The main points of the installation of branch lines.
Generally, the connection point between the branch line and the main line should be equipped with fall protection or disconnect equipment. A set of breaker outlets can be installed on the branch line. If the branch line is long, install another set at 1/2 distance of the branch line. When the line is faulty, first observe the operation of the fault current indicator at the connection of each branch line. If an abnormality is found, first disconnect the line, restore the power supply of other lines, and continue to check the display of the middle line indicator. If the middle section indicator has an indication, the fault point is in the second half of the line. If the middle section indicator is not abnormal, the fault point is in the front half of the line. After narrowing the fault range, it is easy to find the fault point.
The short circuit fault indicator currently used has changed from a single short circuit indicator in the past to a short circuit and grounding indicator. When it is found that only one fault indicator of a certain installation point is red, it means that there is grounding from the installation point of the phase to the load side. If there are two red fault indicators, it means that there is a "short circuit" or "short circuit to ground" phenomenon between the point and the load side. If all three substation fault indicators are red, it means that there is a "short circuit" from this point to the load side, which is generally caused by surrounding trees.
In operation practice, the accurate indication rate of the high voltage fault indicator is low when there is single-phase grounding. The reasons are as follows. When there is single-phase grounding, the voltage unbalanced operation is allowed within 2h. However, the increase of harmonic components and the rise of a certain phase voltage during grounding make the substation Tv sound abnormal, and the alarm equipment frequently alarms, so the duty officer can immediately cancel the operation.
The fault indicator is factory-set for a long time for grounding, generally more than 5min, so when a grounding fault occurs in a phase line, if the substation operator moves quickly, the fault line can be removed from operation within 3min, then the fault indicator will not indicate. If the operator's actions are slow and they stop operation after 5 minutes, then the electric digital indicator will alarm.
There are two solutions to this problem.
1) Change the operation mode to appropriately lengthen the release time of voltage unbalance operation.
2) Contact the manufacturer when ordering the equipment to shorten the grounding action time of the indicator to less than 2 minutes.
When the indicator hangs on the wire, it should be vertical to the ground and not inclined. When the indicator is tilted, it is difficult to rotate when it moves, and it cannot move correctly, or after the fault is eliminated, the indicator does not return to the original position, which will cause a misjudgment.
The indicator should be installed on the power side of the pole tower, not on the load side of the pole tower, with the cross arm as the demarcation point, so that when the equipment component on the pole tower fails, it is still within the indication range of the indicator.