The QJ Series Gas Relay is a protective device designed for oil-immersed transformers and on-load tap changers. It is installed in the pipe connector between a transformer cover and a conservator, and can be fitted with an air duct box for ground exhaustion and sampling. The relay's contacts are designed to connect with a control loop, providing timely signals or automatically cutting off the transformer in cases of oil decomposition, gasification, or oil flow impulses caused by internal transformer failure.
Function Description:
The relay operates based on the accumulation of gas or sudden oil flow. In normal operation, the relay is full of transformer oil. When gas produced by decomposed transformer oil gathers in the upper gas chamber, it forces the oil surface to reduce. This causes the snap ring (float) to lower, and a magnet attached to it actuates a dry reed contact, connecting to the signal circuit to trigger an alarm. In the event of a serious internal transformer failure, the pressure in the oil tank rises instantaneously, causing oil surging. This impulse acts on a guard board, and a magnet on the guard board actuates another dry reed contact, connecting to the tripping circuit to trigger an alarm and cut off the transformer.
The relay's core structure includes a gas lock (1), gas lock nut (2), probe (3), blocking (4), snap ring (float) (5), weights drop (6), guard board (7), magnet (8), connecting terminal (9), spring (10), regulating rod (11), and dry reed contact (12). The gas lock in the cover is used for exhaustion during assembly and for extracting gas. Probe (3) is used to check the flexibility and reliability of the tripping mechanism.
Important Technical Specifications:
- Model Designation:
QJ: Gas relayA: With waterproof covers and gas-collecting boxPipe diameter (nominal valve) mmSerial number designed
- Permissible Operating Temperatures: -30°C to +95°C
- Assembling Method: The relay's pipe axis should be parallel to the transformer case cover. It is permissible for the conservator end to be higher, but the inclination between the axis and the level surface should not exceed 4%.
- Shock Resistance: No accidental operation occurs if the frequency of shock (sine wave) is 4 to 20 Hz and acceleration is 4g.
- Level of Protection: IP5 level of water spray prevention. The product includes a flashing function. A rain screen can be purchased additionally for special cases.
- Sealing Property: No leakage when pressurized to 200KPa for 20 minutes at normal temperature with transformer oil inside.
- Contact Rating (List 1):
- Operating Voltage:
- AC: 220V-250V
- DC: 110V-240V
- Working Current:
- AC: 0.3A~1A (cos Φ ≤ 0.6)
- DC: 0.3A~1A (S ≤ 0.005S)
- Technical Parameters (List 2):
- Pipe Diameter (mm): Φ50, Φ80
- Accumulative Gas Quantity (ml): 250~300
- Oil Speed Setting Range (m/s): 0.6~1.2 (for Φ50), 0.7~1.5 (for Φ80)
- Outlet Number: 1 or 2 (depending on model, e.g., QJ1-50 has 1, QJ3-50 has 2)
- Installation Dimensions (List 3):
- Models vary in D0, H, L, D, A, d, B, and Weight (kg). For example:
- QJ1-50: D0=Φ50, H=220, L=160, D=Φ130, A=120, d=M12, B=100, Weight=10kg
- QJ4-80: D0=Φ80, H=235, L=185, D=Φ160, A=160, d=Φ18, B=100, Weight=13kg
Usage Features:
- Installation:
- Before installation, the relay core must be removed, and any transit bandages disassembled. All fastenings should be checked for flexibility, and the snap ring (float) and guard board should move freely, with contacts opening and closing reliably.
- The relay should be installed in the pipe connector between the transformer's oil tank and conservator, with the internal diameter of the pipe connector matching the relay's pipe diameter. An arrow on the relay must point towards the conservator.
- The conservator end can be higher, but the inclination between the pipe connector's axis and the level surface should not exceed 4% to ensure smooth gas entry into the relay.
- For convenient overhaul, the installation site must allow the relay's core to be smoothly removed from its case (e.g., 130mm for QJ4-25, 150mm for QJ4-50 and QJ4-80).
- After installation, open the valve in the connecting pipe, remove the gas lock dust cover, and unscrew gas lock nut (2) by hand (not completely removing it) to exhaust air until oil spills from the air nozzle, then screw down the nut.
- If connecting to an air dust box, remove blocking screw (4) in the cover before opening the oil valve. Then, screw on joint chair (3), and connect conduct pipe (6) to joint chair (3) with nut (4) and cushion (5). The gas block can then be used normally.
- Electrical Connection: Connections can be made in series or parallel according to the provided diagrams (Fig. 4-1, 4-2, 4-3). Users can customize wiring. To connect, unscrew press line nut (13), thread the cable through the nut hole and rubber ring (14), then screw down nut (13) to secure the cable and prevent water inflow.
- Debugging: QJ series relays are critical protective devices. They should only be brought into service after debugging, examination, and confirmation by an inspection department, following pertinent regulations.
- Gas Volumetric Quantity Adjustment: The volumetric quantity for the signal contact can be adjusted by changing the position of the dry reed contact. Moving it upwards reduces the volume, and moving it downwards increases it. The screw should be firmly tightened after adjustment.
- Oil Speed Adjustment: The acting oil speed is adjusted by changing the pulling force of the baffle board spring via the regulating rod connected to the spring. This adjustment should be performed by professionals using a special flow rate checking facility.
- Baffle Board's Angle of Rotation Adjustment: The baffle board's angle of rotation can be adjusted by changing the backstop screw. This involves adjusting the distance (0.5~1.0mm) between the magnet and the dry reed contact to ensure reliable opening and closing.
- Checking Reliability:
- Pump gas in from nozzle (1) to check the reliability of the "signal" contact.
- Remove the probe cover and press probe (2) to check the reliability of the "tripping" contact.
- Collecting Gas Sample: To collect a gas sample while in service, remove the gas lock dust cover, insert a rubber tube into the air nozzle, unscrew the gas lock nut, and fill the bottle. Screw down the nut and fix the dust cover after sampling.
Maintenance Features:
- Annual Inspection: An inspection of the relay's appearance and the reliability of both the signal and tripping circuits should be performed annually.
- Biennial Inspection: Relays in service should be opened up every two years to inspect their internal structure and action reliability.
- Five-Year Tests: Power frequency and breakdown tests of relays in service should be conducted every five years.
- Notice:
- The magnet should not be acutely vibrated, placed in a strong magnetic field, or exposed to temperatures higher than 100°C or lower than -40°C to prevent demagnetization.
- Do not disassemble the dry reed contact at will, especially avoid bending the root of the lead to prevent damage.
- Warranty: The company provides a three-guarantee policy for the product. The warranty period is 18 months from installation or 24 months from delivery, whichever comes first. Users must operate the product according to the instruction manual.
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