There are a variety of protection devices that can be installed on the general transformer in order to ensure that the power system is continuously and safely operated:
1.Protecting against gas leaks
A number of faults and a reduction in oil level inside the transformer tank can be seen in the graph. Act on all sides to trip and signal. Transformers can be protected against internal faults by gas protection devices. The gas protection should activate when a fault occurs inside the transformer, when the oil is decomposed by heat to produce gas, or when the transformer’s oil level decreases.
Transducers with a capacity of 800KVA and above should be protected from gas in general, and transformers in workshops should be protected from gas in general. On the power supply side, the light gas action triggers a warning signal, and the heavy gas action triggers the circuit breakers.
2.Protection on a longitudinal basis
Faults such as short circuits between phases of transformer windings and lead wires, short circuits between turns of windings, and single-phase ground short circuits are reflected. All sides of the protection action are involved. By using the longitudinal differential protection device, the internal fault of the transformer and the lead-out bushing can be prevented.
The transformers with a capacity of 10000kva or more running in a single unit and the transformers with a capacity of 6300kva or more running in parallel shall be equipped with longitudinal differential protections. Longitudinal differential protection can also be used when quick-break protection does not meet the requirements.
3.Quick-break protection currently in place
Phase-to-phase short circuit backup protection: As a backup for gas and differential protection, it protects against phase-to-phase overcurrents caused by external short circuits. The protection delay action when tripped.
Current quick-break protection can be used to protect against transformer internal faults and lead-out bushing faults.
In transformers with capacities below 10000kva and transformers running in parallel with capacities below 6300kva, the current quick-break protection generally replaces the longitudinal differential protection. If the sensitivity of the transformer does not meet the requirements, longitudinal differential protection should be installed.
4.Protection against zero sequences
This represents a grounding short circuit of the transformer neutral point directly grounded system windings, outgoing wires, and adjacent components (busbars and lines). The protection delay action when tripped.
5.Protection from overcurrent
Transformers can be protected against internal and external faults with overcurrent protection. Overcurrent protection with time limit acts as backup protection for longitudinal differential protection or current quick-break protection by tripping power supply circuit breakers.
6.Protection against overload
It indicates the overload condition of each side of the transformer or the autotransformer’s common winding.
Signals are affected by the protection delay. Transformers are protected from overcurrent caused by overload by overload protection. Protection devices are only connected to a certain phase of the circuit and delay action on the signal, trip, or automatic load shedding.
7.Grounding protection for single-phase systems
When the protection sensitivity of the high-voltage side does not meet the requirements, special zero-sequence current protection is installed on the low-voltage side of the neutral point directly grounded system (three-phase four-wire system).
8.Protection against overheating (cooler full stop):
The temperature of the transformer’s windings or oil is reflected in this value. Protection trips on both sides have a long delay.
