As with any electronic device, environmental factors can affect the operating and starting performance and health of transformers. In particular, transformers used in cold climates may need to be started more cautiously when the temperature drops below a certain level.
Under normal conditions, transformers with energy ratings below 69kV do not require preheating or other starting procedures. However, this process changes for equipment operating in cold climates.
At what temperature should the cold weather start protocol be applied?
The Institute of Electrical and Electronics Engineers (IEEE) in the USA recommends that transformers operating at -20 degrees Celsius or colder should be started using the cold start protocol. However, this value varies depending on the characteristics of the equipment. The most accurate information on how many degrees to start your transformer using the cold start protocol is provided by the manufacturer.
Things to consider when starting a cold weather transformer
When starting your transformer in unseasonably cold weather, there are a few things to consider.
Check oil temperature and viscosity
In cold weather, the viscosity of the oil in transformers increases and its fluidity may decrease. This can prevent the oil from circulating properly and efficiently in the transformer tank.
It is recommended that the oil viscosity and temperature be checked before starting the transformer and that the transformer be allowed to warm up if necessary.
Oil-Water Saturation and Dielectric Strength
At low temperatures, water saturation in transformer oil can increase, which can reduce the dielectric strength.
In such cases, it is important to take oil samples and measure the water content, making sure it is saturated to the limits of the oil type.
Initialization Procedure
After energizing your transformer, it is recommended that it be allowed to idle in the soak position for at least eight hours. This will allow the oil in your transformer to reach the desired temperatures and reduce its viscosity.
At the end of the eight hours, you can begin to use your transformer by gradually increasing the load, preferably in 10-20% increments. It is recommended to wait 30 minutes between load increases to reduce mechanical and electrical stress.
Cold weather transformer startup is an application that must be handled with care. It is important to monitor transformer temperatures, oil levels and other critical parameters throughout the startup process. In the event of abnormalities or unexpected changes, it is best to stop the process and consult a qualified technician.