Rơ le hơi, Transformer Gas Relay QJ2-40TH QJ3-40TH

working principle:
 
　　When the transformer is in normal operation, the inside of the gas relay is filled with transformer oil. When there is a fault inside the transformer, the gas generated by the decomposition of the transformer oil collects in the gas collecting chamber of the relay. The air pressure forces the oil level to drop, the float decreases with the oil level, and the magnetic switch is connected in parallel. K1 or K2 is closed (QJ2-40TH-S type K1a, K2a closed, K1b, K2b open). 

When the gas reaches the alarm gas volume, the magnetic switch K1 is sucked (QJ2-40TH-S type K1a is closed, K1b is turned on), the signal circuit is turned on, and an alarm signal is issued. If the oil level in the fuel tank drops due to other reasons (such as oil leakage), the alarm circuit is also applied to the signal circuit. 

When a serious fault occurs inside the transformer, a large amount of gas will be generated. When the gas reaches the volume of the cut gas, the magnetic switch K2 is sucked (QJ2-40TH-S type K2a is closed, K2b is turned on), a cutting signal is issued, and the cutting device is operated. The transformer is cut off from the grid to protect the transformer. 

The main technical parameters:
 
● Working temperature: -30 ° C ~ +120 ° C
 
● Pipe diameter: φ40mm
 
●Contact capacity: AC 220V 1A DC 220V 0.5A
 
● Sealing test pressure: 200kPa 20min 
Production considerations:
The waterproof measures of the main body gas relay of the transformer are not perfect. When it rains or when the snow melts, the water droplets are easily dripped into the junction box through the oil pillow. Lightning will cause DC ground fault, but the transformer protection will cause false vibrations, light gas signals and even heavy gas protection actions, causing switching on both sides of the transformer. .

5 Installation and commissioning

5.1 Installation 
of the relay 5.1.1 The relay of the new factory must be taken out before use and the tie-in strap for transport fixing must be removed. Also check whether all the fasteners are loose, whether the open cup (float) and the baffle are flexible, and whether the contacts are reliably opened and closed. 
5.1.2 The relay shall be installed on the connecting pipe between the oil tank of the oil-immersed transformer and the oil conservator. The inner diameter of the connecting pipe shall be the same as the pipe diameter (caliber) of the relay. The arrow on the relay must point to the oil conservator. . Allow the oil storage tank end to be slightly higher, but the inclination of the axis of the joint pipe and the horizontal plane shall not exceed 4%, or the method of installing the inclined gas pipe shall be adopted to make the gas inside the transformer smoothly enter the relay. 
5.1.3 In order to facilitate the inspection of the gas relay at the operating site, the installation position should ensure that the relay core can be smoothly removed from the housing. The QJ4-25 type has a height of 130mm, and the QJ-50 and 80 have a height of 150mm. 

5.2 Debugging 
gas relay is an important protection device for oil-immersed transformers. Therefore, the operating department has special regulations. For example, it must be commissioned, calibrated and certified by the inspection department before it can be put into use. Therefore, commissioning and oil speed setting work should be carried out in accordance with relevant regulations. . 
5.2.1 Adjustment of gas volume 
change The position of the reed contact can be adjusted to adjust the gas volume of the signal contact. When the reed contact moves up, the gas volume decreases, and when the reed contact moves down, the gas volume increases. Tighten the locking screws after adjustment. 
5.2.2 Adjusting the oil speed Adjusting the 
spring-connected adjusting rod can change the pulling force of the baffle spring, and can change the oil speed of the tripping contact action (the relay is set at the factory, the value is shown in the certificate), and should be locked after adjustment. Nut. The action speed setting work should be performed by a professional on a dedicated flow rate calibration device. 
5.2.3 Adjusting the rotation angle of the baffle 
Adjusting the stop screw can change the rotation angle of the baffle to adjust the distance between the magnet and the reed contact (0.5~1.0mm), so as to ensure the reliable opening and closing of the reed contact. 

6 Maintenance, repair

6.1 The relay shall be visually inspected annually for reliability and reliability of the signal loop and reliability of the trip circuit. 
6.2 The relay that has been operated should be opened once every two years for internal structural and operational reliability checks. 
6.3 The relay that has been operated shall be tested for the power frequency withstand voltage every five years.