1762-OW16 瓦斯继电器的引出线应采用防油线或塑料线

Description

1762-OW16 瓦斯继电器的引出线应采用防油线或塑料线

1 使用安全措施

长期以来，瓦斯保护正确动作率低于变压器其他保护装置的平均水平，为提高瓦斯保护的安全可靠性，除改进瓦斯继电器的结构以外，需要执行以下安全技术措施。

变压器应有1%～1.5%的坡度。通往继电器的油管应有２%～４%的坡度，油枕处较高，使气体易流入瓦斯继电器

瓦斯继电器的引出线应采用防油线或塑料线，经过中间接线盒，通过端子排和电缆连接，电缆和引出线应分别连接在接线盒内端子排的两侧，引出线从端子排下方接入电缆从端子排上方引出，这样接线是为了避免由于油的毛细管现象引起对电缆的腐蚀。此外还应注意，引线排列要使重瓦斯接点和直流电源正极隔开，中间端子盒不要安置在油管和油枕下面，以防油管和油枕漏油渗入端子盒。

防止瓦斯继电器接点引出线因漏水短路，瓦斯继电器的端盖部分和电缆引出线的小端子箱应有密封措施，以防止雨水浸入造成误动作。

瓦斯继电器的出口中间继电器应带自保持线圈，以防止变压器内部严重故障时油速不稳定，造成瓦斯接点时通时断而不能可靠跳闸。

变压器的呼吸器必须保持通畅，变压器投入之前，必须检查吸湿器下部的透气孔是否开启。运行中也应检查吸湿器的透气情况，以防止变压器油温变化时，因透气孔闭塞造成呼吸器或油枕真空或压力升高，使瓦斯继电器误动作。

瓦斯继电器和储油柜间的连接阀门运行时应打开，为防止检修后遗忘开启，造成瓦斯误动作，阀门应加铅封。

变压器运行时，重瓦斯应接入跳闸，轻瓦斯投入信号。备用变压器的瓦斯应投入信号，以便监视油面。备用的单台变压器应断开跳闸电源。当一台断路器控制两台变压器时，若其中一台转为备用，应将其重瓦斯改接信号。

变压器在运行中进行滤油、加油、换硅胶或在散热器、潜油泵检修后投入前，应先将重瓦斯接信号，待空气排尽后，方可将重瓦斯投入跳闸位置。

当油位计上指示的油面有异常升高或油路系统有异常现象时，为查明原因，需要打开各个放气或放油塞子、阀门，检查吸湿器，或在进行其他工作时必须先将重瓦斯改接至信号，然后才能开展工作，以防瓦斯保护误动作跳闸。

2 瓦斯保护信号动作的主要原因

若瓦斯保护动作，变压器开关跳闸，一般情况下，其事故过程已结束，后果比较严重。因此，必须在瓦斯信号动作时，认真检查，仔细分析，正确判断，立即采取措施。变压器瓦斯继电器有浮筒式、挡板式、开口杯式等不同型号，目前大多采用QJ-80型瓦斯继电器，其信号回路接上开口杯，跳闸回路接下挡板。所谓瓦斯保护信号动作，是指因各种原因造成继电器内上开口杯的信号回路接点闭合，轻瓦斯动作。接点闭合的原因一般有以下几方面。

1762-OW16 瓦斯继电器的引出线应采用防油线或塑料线

1 Use safety measures

For a long time, the correct operation rate of gas protection is lower than the average level of other transformer protection devices, in order to improve the safety and reliability of gas protection, in addition to improving the structure of gas relays, the following safety technical measures need to be implemented.

The transformer should have a slope of 1% to 1.5%. The oil pipe leading to the relay should have a slope of 2% to 4%, and the oil pillow is high, so that the gas is easy to flow into the gas relay

The outgoing cable of the gas relay should be oil-proof or plastic, and connected to the cable through the terminal block through the intermediate terminal box. The cable and the outgoing cable should be connected to both sides of the terminal block in the terminal box, and the outgoing cable should be connected from below the terminal block to the cable from above the terminal block. This connection is to avoid the corrosion of the cable caused by the capillary phenomenon of oil. In addition, it should be noted that the lead arrangement should be separated from the heavy gas contact and the positive DC power supply, and the middle terminal box should not be placed under the oil pipe and oil pillow to prevent oil leakage into the terminal box.

To prevent short circuit of the gas relay contact outlet line due to water leakage, the end cover part of the gas relay and the small terminal box of the cable outlet line should be sealed to prevent misoperation caused by rainwater immersion.

The outlet intermediate relay of the gas relay should be equipped with a self-holding coil to prevent the oil speed from being unstable when the transformer is in serious internal fault, resulting in the gas contact being on and off and unable to reliably trip.

The transformer respirator must be kept open, and before the transformer is put in, it must be checked that the ventilation hole under the moisture absorber is open. During operation, the air permeability of the moisture absorber should also be checked to prevent the vacuum or pressure rise of the breathing apparatus or oil pillow due to the occlusion of the air vent when the oil temperature of the transformer changes, causing the gas relay to operate incorrectly.

The connecting valve between the gas relay and the oil storage tank should be opened during operation. In order to prevent the forgotten opening after maintenance, causing gas misoperation, the valve should be sealed with lead.

When the transformer is running, heavy gas should be connected to tripping and light gas input signal. The gas of the backup transformer should be put into the signal to monitor the oil level. The spare single transformer should be disconnected from the trip power supply. When a circuit breaker controls two transformers, if one of them is switched to standby, its heavy gas should be switched to signal.

Before the transformer is put into operation after oil filtering, refueling, changing silica gel or after the repair of the radiator and submersible oil pump, the heavy gas should be connected to the signal first, and the heavy gas can be put into the tripping position after the air is exhausted.

When there is an abnormal rise in the oil level indicated on the oil level gauge or an abnormal phenomenon in the oil circuit system, in order to find out the cause, it is necessary to open each gas or oil drain plug, valve, check the moisture absorber, or in other work must first change the heavy gas to the signal, and then work to prevent the gas protection from misoperation and tripping.

2 Main reasons for gas protection signal action

If the gas protection action, the transformer switch trip, under normal circumstances, the accident process has ended, the consequences are more serious. Therefore, it is necessary to carefully check, carefully analyze, correctly judge and take immediate measures when the gas signal is in action. There are different types of transformer gas relays, such as float type, baffle type and open-cup type. At present, most of them use QJ-80 type gas relays, whose signal circuit is connected to the open-cup and the tripping circuit takes over the baffle. The so-called gas protection signal action refers to the signal circuit contact of the upper open cup in the relay that is closed and the light gas action is caused by various reasons. The reasons for contact closure generally have the following aspects.