13.8 Kv Single Phase Potential Transformer in Substation

Product Features:

A 13.8 Kv Single Phase Potential Transformer in Substation is designed to step down the primary voltage of 13.8 kv to a standard secondary voltage, such as 100 or 110 volts. The reduced voltage is then supplied to the parallel windings to measure instruments and protective relays, enabling primary voltage measurements to be made indirectly with a low voltage instruments. Such an approach simplifies instrument design, saves cost, and ensures the safety of both equipment and operating personnel.

The working principle of a 13.8 kv single phase potential transformer is as the same as a power distribution transformer, of which the transformation ratio is determined by the number of turns in the primary and secondary coils. Increasing the number of secondary turns reduces the ratio, while increasing the number of primary turns raises it. It is important to note that under no circumstances should the secondary circuit of a 13.8 kv single phase potential transformer be short circuited during operation.

Technical Specification:

Product FAQ:

Q: How is a 13.8 kv single phase potential transformer different from a 13.8 kv power transformer?

A: While both are voltage converting devices, a 13.8 kv single phase potential transformer is designed for measurement and protection rather than power transfer. Its rated burden is relatively small, usually expressed in VA, whereas power transformers handle loads in a larger value which counts in kVA or MVA.

Q: What insulation methods are used at a 13.8 kv single phase potential transformer?

A: Most potential transformers at this voltage level employ epoxy resin cast insulation for indoor service or porcelain/silicone housings for outdoor installations. Some designs use oil immersed insulation to achieve an extended service life and higher thermal capacity.

Q: How should a 13.8 kV single phase potential transformer be connected in a substation?

A: For phase to ground measurement, the PT primary is connected between one phase and ground. In a three phase system, a set of single phase PTs or a three phase PT unit can be used to measure line to line and line to ground voltages.

Q: What issues can arise with 13.8 kV single phase potential transformers in substations?

A: Common problems include insulation degradation, ferroresonance under certain switching conditions, overheating due to over burdening, and secondary circuit open conditions that may cause dangerously high voltages.