【Daily Topic】【Electrical Edition 20160707】

(1) Gas protection. It is used to indicate various faults within the transformer tank as well as a drop in the oil level. (2) Differential protection. Used to indicate faults in the transformer windings, bushings, and leads. (3) Inter-phase overcurrent protection. Depending on the operating conditions, composite voltage blocking and direction blocking can be introduced, and according to the setting requirements, it is possible to detect inter-phase short-circuit faults inside and outside the transformer. (4) Impedance protection. When the inter-phase overcurrent protection does not meet the sensitivity requirements, impedance protection can be used. (5) Zero-sequence current protection and zero-sequence current direction protection. Depending on the setting direction, it can reflect internal and external ground short-circuit faults of the transformer. (6) Overload protection. Reflects the overloaded condition of the transformer; triggers a signal or trip. (7) Over-excitation protection. It reflects the over-excitation condition caused by overvoltage or reduced frequency, and acts on the signal or to trigger a trip. (8) Other protections. Protection that reflects special conditions such as pressure release and temperature rise.

Overcurrent protection, quick-break protection, differential protection, gas protection, single-phase grounding protection, temperature protection, overload protection.

(1) Gas protection. It is used to indicate various faults within the transformer tank as well as a drop in the oil level. (2) Differential protection. Used to indicate faults in the transformer windings, bushings, and leads. (3) Inter-phase overcurrent protection. Depending on the operating conditions, composite voltage blocking and direction blocking can be introduced, and according to the setting requirements, it is possible to detect inter-phase short-circuit faults inside and outside the transformer. (4) Impedance protection. When the inter-phase overcurrent protection does not meet the sensitivity requirements, impedance protection can be used. (5) Zero-sequence current protection and zero-sequence current direction protection. Depending on the setting direction, it can reflect internal and external ground short-circuit faults of the transformer. (6) Overload protection. Reflects the overloaded condition of the transformer; triggers a signal or trip. (7) Over-excitation protection. It reflects the over-excitation condition caused by overvoltage or reduced frequency, and acts on the signal or to trigger a trip. (8) Other protections. Protection that reflects special conditions such as pressure release and temperature rise.

The primary protections installed in power transformers include: 1. Gas protection (to detect faults inside the transformer itself); 2. Differential protection (to detect faults within the current transformers on each side of the transformer). The secondary protections installed in power transformers include: 1. Composite voltage-locked overcurrent protection; 2. Negative sequence current protection; 3. Resistance-based protection; 4. Zero sequence overcurrent protection; 5. Zero sequence overvoltage protection; 6. Overload protection; 7. Overtemperature and overpressure protection; 8. Cooling system protection; 9. Other specialized protections

①Gas protection (reflecting internal faults in the transformer itself)； ②Differential protection (detects faults within the current transformers on each side of the transformer). (2) The backup protections installed in power transformers include ① load voltage-locked overcurrent protection ； ②Negative sequence current protection ； ③Resistance group protection ； ④Zero-sequence overcurrent protection ； ⑤Zero-sequence overvoltage protection ； ⑥Overload protection ； ⑦Over-temperature and over-pressure protection ； ⑧Cooling system protection ； ⑨Other specialized protections. The specific type of protection to be installed should be selected appropriately in accordance with relevant relay protection regulations and specifications, taking into account the transformer’s capacity and its role in the power grid.

(1) Gas protection. It is used to indicate various faults within the transformer tank as well as a drop in the oil level. (2) Differential protection. Used to indicate faults in the transformer windings, bushings, and leads. (3) Inter-phase overcurrent protection. Depending on the operating conditions, composite voltage blocking and direction blocking can be introduced, and according to the setting requirements, it is possible to detect inter-phase short-circuit faults inside and outside the transformer. (4) Impedance protection. When the inter-phase overcurrent protection does not meet the sensitivity requirements, impedance protection can be used. (5) Zero-sequence current protection and zero-sequence current direction protection. Depending on the setting direction, it can reflect internal and external ground short-circuit faults of the transformer. (6) Overload protection. Reflects the overloaded condition of the transformer; triggers a signal or trip. (7) Over-excitation protection. It reflects the over-excitation condition caused by overvoltage or reduced frequency, and acts on the signal or to trigger a trip. (8) Other protections. Protection that reflects special conditions such as pressure release and temperature rise.

I. Inter-phase short circuits of the windings and their leads, as well as single-phase ground short circuits on the side with directly grounded neutral point； 　　II. Inter-turn short circuit of the windings ； 　　III. Overcurrent caused by external interphase short circuits ； 　　IV. Overcurrents and neutral overvoltages caused by external ground faults in power grids with directly grounded neutral points ； 　　V. Overload ； 　　VI. Decrease in oil level ； 　　VII. Rise in transformer temperature, increase in tank pressure, or failure of the cooling system.

It features overcurrent protection, instantaneous current protection, longitudinal differential protection, single-phase ground fault protection on the low-voltage side, overload protection, gas protection, temperature protection, and more

Current speed break protection, interconnected differential protection. Dual differential protection operates with a time-delayed trip. Overcurrent protection, impedance protection. Circuit breakers on each side.