Voltage transformer is an electrical device used in power systems to convert high voltage into low voltage, mainly for measurement, protection, and control. Its safe use must meet the following conditions to ensure personnel safety and equipment normal operation:

1、 Basic safe operating conditions for voltage transformers:

1. Matching of rated parameters

Primary side voltage: It should be consistent with the system voltage level to avoid overvoltage or undervoltage operation.

Secondary side load: Ensure that the secondary circuit load does not exceed the rated capacity of the transformer, otherwise it may cause measurement errors or heat damage.

Accuracy level: Select the appropriate accuracy level based on the purpose.

2. Wiring correctness

Polarity connection: The polarity of the primary and secondary sides must be correct to avoid protection misoperation caused by phase reversal.

Grounding requirements:

The primary winding (high voltage side) needs to be connected to the high voltage equipment through an insulating sleeve, without the need for direct grounding.

The secondary winding (low voltage side) must be reliably grounded (usually at the end of the transformer housing or secondary winding) to prevent the high voltage from the primary side from entering the secondary circuit and causing the risk of electric shock.

Prohibition of short circuit: The secondary side must not have an open circuit (especially during operation), otherwise it may cause overheating and burning of the iron core or high voltage danger due to a sharp increase in magnetic flux.

3. Insulation and Protection

Insulation performance: Regularly check the insulation resistance between the primary and secondary sides of the transformer to ensure compliance with specifications.

Waterproof and moisture-proof: Transformers installed outdoors must have a waterproof rating to prevent internal moisture and short circuits.

Physical protection: The installation location should be away from high temperatures, vibration sources, and chemical corrosion environments.

2、 Safety precautions during the operation of voltage transformers

1. Prevent secondary side open circuit

Risk: When the secondary side is open circuited during operation, all the primary side current becomes excitation current, causing the iron core to saturate and inducing high voltage (possibly thousands of volts), endangering personal safety and damaging equipment.

measures:

Power must be cut off before operating the secondary circuit;

When replacing instruments or wiring, it is necessary to use a short circuiting tool (such as a dedicated short circuiting piece) to temporarily connect the secondary circuit.

2. Prevent primary side short circuit

Risk: A short circuit on the primary side can generate a large current, causing the transformer to overheat and explode.

measures:

Ensure that the primary winding is firmly connected to the high-voltage equipment during installation;

Regularly check the condition of the side insulation sleeve and wiring terminals.

3. Temperature monitoring

Allow temperature rise: During operation, the surface temperature of the transformer must not exceed the rated limit. Abnormal temperature rise may indicate overload or internal faults.

Infrared temperature measurement: Regularly use an infrared thermometer to detect the temperature of the transformer body and joints.

4. Harmonics and transient interference

Harmonic impact: Harmonics in the power system may cause measurement errors in transformers or overheating of iron cores, requiring the installation of filtering devices.

Transient overvoltage: Lightning strikes or operational overvoltage may cause damage through coupling and require the use of lightning arresters or surge protectors.