Outdoor dry type transformer installation requirements

Can dry type transformers be installed outdoors?

‌Dry type transformers can be installed outdoors, but special protective measures are required.

Special protective shell: When dry type transformers are used outdoors, special protective shells need to be configured, such as the IP44 shell which can protect the side from water but does not provide the top cable inlet and outlet‌.

Platform installation: Dry type transformer in outdoor use is usually installed on the special platform. Such platform is called dry transformer station ‌.

Outdoor dry type transformer installation requirements

1.‌Installation method: Outdoor dry type transformer can be installed on the ground or on the column. The transformer capacity of 315kVA or less can be installed on the column. The transformer capacity of more than 315kVA should be installed on the ground ‌.

2.‌ Environmental conditions: Dry type transformer in outdoor use needs to meet the following environmental conditions:

The altitude does not exceed 1000 meters.

Ambient temperature: maximum temperature +40℃, maximum daily average temperature +30℃, maximum annual average temperature +20℃, minimum outdoor temperature -30℃, minimum indoor temperature -5℃‌.

Avoid rain, humidity, high temperature, high heat or direct sunshine. The distance between the heat dissipation vent and surrounding objects should be not less than 40cm‌.

3.‌ Installation position and fixing method:

Column installation: the bottom distance from the ground shall not be less than 2.5 meters, the live part from the ground shall not be less than 3.5 meters. The transformer on the column must be installed steadily and firmly. 

‌Ground installation: it should be installed on a cement platform with sufficient bearing capacity and a height of 0.5 meters. Fences should be set up around the transformer. The height of the fences should not be less than 1.7 meters and warning signs should be hung in obvious parts. The fence shall not be less than 1 meter from the transformer outline. And in the direction of operation, the distance shall not be less than 2 meters ‌.

Why can't dry type transformers be directly used outdoors？

The current dry type transformer, if used directly in the outdoors, has the following three insulation problems:

1.The tension structure of the iron core is channel steel and pull plate structure. In this structure, pull plate is located between the coil and the iron core. The material of the pull plate is iron and is easy to rust. In addition, the outdoor weather is bad and the insulation layer on the outer surface of the pull plate is easy to destroy which results in short circuit damage to the transformer.

In addition, the pull plate is located between the coil and the iron core, occupying a certain space. The inner diameter of the coil is increased and wasting coil materials and increasing power consumption.

2. The self-drying resin insulating paint layer on the surface of the iron core is easy to weather, crack after the sun and rain. After a certain time, a series of problems will appear, for example, the surface of the iron core rust, short circuit between iron chips, no-load loss and no-load current increase and so on.

3.Low voltage coils and high voltage coils are cast with epoxy resin, and the anti-cracking and anti-ultraviolet resistance of epoxy resin is not strong. This dry type transformer is used in the outdoors and the epoxy resin will crack after long-term exposure to the sun, wind and rain. Finally the insulation is completely damaged, resulting in short circuit of the coil.

Maintenance and inspection of outdoor dry type transformer

1.Periodic check: Periodically check the device and handle any problems in a timely manner to ensure the stability and reliability of the device.

2.Clean the device: Periodically clean the surface of the device to ensure good heat dissipation and normal operation of the device.

3.Lightning protection grounding check: Periodically check the lightning protection grounding device of the device to ensure that the device can work properly when struck by lightning.