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1. Reasons for the high room temperature of the transformer

The area of the ventilation window of the transformer room in the national standard drawing 88D264 (hereinafter referred to as the national standard drawing) is that the calculated temperature of the transformer room does not exceed +35°C (calculated temperature of the inlet air), the temperature of the outlet air is 45°C, and the temperature difference between the inlet and outlet air does not exceed +35°C (calculated temperature of the inlet air) according to the summer ventilation calculation of the transformer room. The area of the ventilation window in the transformer room is designed for conditions exceeding 15°C. The transformer manufacturer stipulates that the ambient air temperature of the transformer should not exceed +40℃ in normal use. The ventilation condition of the national standard drawing is 5℃ higher than the normal use environment temperature specified by the manufacturer. The transformer room designed according to the size of the transformer chamber in the national standard drawing no longer meets the requirements of the transformer for the surrounding air temperature. The highest temperature in summer is also electrical When the load is maximum, the air temperature around the transformer is high, the load is heavy, and the temperature rise of the transformer itself is too high, and the transformer failure is inevitable.

In the national standard drawing 88D264, the area of the ventilation window of the given transformer room is the effective area, and the effective area coefficient of the ventilation window is less than 1. Part of the design did not notice the difference between the area and the effective area, and the area required in the standard drawing was designed. The conditions were put forward to the civil construction, and the area of the ventilation windows in the actual transformer room was once again discounted. The area of the ventilation window does not meet the requirements of transformer operation.

The ninth paragraph of Article 6.0.1 of GB 50060-92 stipulates that "the indoor passage of the power distribution device shall be guaranteed to be unblocked, no threshold shall be established, and no pipelines unrelated to the power distribution device shall pass." In some areas, to prevent rodents from entering, a 0.6m high rat-proof gate or threshold is set at the gate of the transformer room. The upper and lower shutters of the transformer room door are added with screens. A large area of the air inlet shutters at the lower part of the transformer room door is just covered. Blocking makes the effective area of the air inlet window of the transformer room smaller and the ventilation effect worse.

The size of the transformer room in the new substation is limited by the column spacing of the entire building. Some transformer rooms are too deep. The transformer is located far away from the wind inlet and outlet shutters on the wall of the substation, so that the The ventilation effect has been compromised again.

When the newly-built transformer room is part of the built standard factory building, the design height of some transformer rooms is subject to certain restrictions. For the transformer rooms of 1600kVA and 2000kVA, some areas still require the use of bench-type layout, and the ventilation effect is poor.

In order to increase the distance between the input and output terminals of the transformer, the transformer is installed on a steel platform. The temperature in the transformer room varies with the height from the ground. The higher the height from the ground, the higher the temperature. The transformer is installed on the steel platform. The rack is in a higher position from the ground, which puts the transformer in a disadvantageous position of higher indoor temperature.

Although an exhaust fan has been installed beside the outlet louvers of the transformer room for forced ventilation, the airflow of the exhaust fan and the airflow of the outlet louvers are close to each other and short circuit, resulting in the efficiency of the exhaust fan. Not fully utilized.

Transformer operation loss heats indoor air, and the rising of hot air forms a flow channel with the inlet and outlet louvers. The greater the height difference between the inlet and outlet louvers, the higher the air flow speed, the better the ventilation effect. In the lower part of the transformer room door and the top wall of the transformer room, there are louvers for air inlet and outlet, but some transformer rooms also have louvers on the upper half of the transformer door, that is, they are opened in the middle of the upper and lower air inlet and outlet louvers. The ventilation effect is reduced.

The load supplied by the transformer is increasing year by year, the transformer is overloaded, and the transformer has not been increased in time. Fortunately, with the advancement of science and technology and the improvement of transformer design and manufacturing technology, the loss of the transformer is decreasing, and the overload capacity is increasing, which relieves some transformers Elevated room temperature causes problems.

However, some transformers still have quality problems such as excessive loss.