2023-06-29 10:28

What are the instructions for using current transformers?

Current transformer protection accuracy level of the old standard (GB1208-75) code "C" "D" "B" respectively, "differential" "dynamic" "protection. "GB1208-87 and GB1208-97 stipulate that: for protection current transformers, the accuracy level shall be expressed as the percentage of the permissible compound error of the accuracy level under the primary current of the rated accuracy limit, followed by the percentage of the permissible compound error of the primary current of the rated accuracy limit. Percentage nominal, followed by the letter "P" for protection, protection current transformer standard accuracy level for 5P and 10P. e.g.: 10P15, "P" in front of the "10 "P" in front of the "10" that in the rated accurate limit of primary current (value of 15 times the rated primary current) when the compound error is not more than 10%, P followed by "15" that its accuracy limit coefficient (10% multiplier, saturation multiplier) for 15 times.

2023-06-29 10:27

What are current and voltage transformers?

Current transformers are used to convert large currents in the primary circuit into small currents in the secondary circuit to supply measuring instruments, meters, relay protection and other similar appliances. Voltage transformer is to transform the high voltage of the primary circuit into low voltage in proportion to the supply of measuring instruments, meters, relay protection and other similar appliances.

2023-06-29 10:26

What is the difference between a voltage transformer and a current transformer?

The main difference is that the normal operation of the working state is very different, mainly manifested as: (1) current transformer secondary can be short-circuited, but not open circuit; voltage transformer secondary can be open circuit, but not short-circuited (2) for the secondary side of the load, the voltage transformer, a small or even negligible internal impedance, can be considered as a voltage transformer is a voltage source; and current transformer, a but the internal resistance is very large, to the extent that it can be considered as a current source of the internal resistance of the infinity of the current source. (3) voltage transformer normal operation of the flux density is close to the saturation value, the failure of the flux density decreases; current transformer normal operation of the flux density is very low, and short-circuit due to the primary side of the short-circuit current has become very large, so that the flux density increases greatly, and sometimes even far more than the saturation value. (4) voltage transformer is used to measure the high voltage of the grid special transformer, it can be converted to a higher voltage in accordance with the specified ratio of lower voltage, and then connected to the instrument to measure. Voltage transformer, the primary voltage, no matter how many volts, and the secondary voltage are generally specified as 100 volts, in order to supply the voltmeter, power meter and kilowatt-hour meter and the voltage coil of the relay voltage required. The large current is converted to a small current in a specified ratio of electrical equipment, known as the current transformer. The current on the secondary side of the current transformer is generally specified as 5 A or 1 A to supply the current to the current coils of ammeters, power meters, kilowatt-hour meters and relays.

2023-06-29 10:24

What types of wiring are available for current transformers?

Current transformer wiring, there are two current transformers using two-phase V-shaped wiring and two-phase current difference wiring; three-phase Y-shaped wiring, three-phase △-shaped wiring and zero sequence wiring using three current transformers.