The common technical parameters of current transformers have rated capacity, rated current ratio, rated current ratio, accuracy level, ratio, angularity, etc. And install specifications "for specific analysis!
1, rated capacity
The rated quadratic current consumes power when the secondary rated load is consumed. The rated capacity can be used in power V.A, or it can be expressed in secondary rated load impedance ω.
2, a rated current
The electric load current is allowed to be a power-load current through a current transformer. The current transformer used in the power system is 5 to 25000A, and the precision current transformer for the test equipment is 0.1 to 50000A. Current transformers can operate for a long time at a rated current, and the load current is called overload, and the current transformer has long-term overload operation, and it will burn the winding or reducing the service life.
3, secondary rated current
Allows one induction current of the secondary winding of the current transformer.
4, rated current ratio (ratio)
The ratio of the rated current and the secondary rated current.
5, rated voltage
The maximum voltage (valid value of the first winding can be spaced (effective value in kv) should not be lower than the rated phase voltage of the connected line. The rated voltage of the current transformer is divided into several voltage levels such as 0.5, 3, 6, 10, 35, 110, 220, 330, 500 kV.
6, 10% times
At the specified secondary load and any power factor, the current error of the current transformer is -10%, the multiple of the primary current to its rated value. 10% of the number of technical indicators related to relay protection.
7, accuracy level
Indicates the level of the transformer itself (specific difference and angularity). At present, the accuracy level of current transformers is divided into 0.001 ~ 1 level, and it is much larger than the original accuracy. The electrical instrument used in power plants, substations, and electrical unit distribution control discs generally use 0.5 or 0.2; for equipment, relay protection of lines is generally not less than 1 level; when electrical energy is measured, The measurement load capacity or the amount of electricity is based on the requirements requirements (see first ").
8, ratio
The error of the transformer includes two parts of the ratio and angularity. The ratio error is referred to as a ratio. Generally, the symbol f is generally indicated, which is equal to the difference between the actual secondary current and the primary current of the secondary side, and the ratio of the primary current that is converted to the secondary side, is expressed in a percentage.
9, angle difference
The phase angle error is referred to as the angle, and is generally represented by symbol δ, which is a phase difference between the secondary current vector and the primary current vector after 180 °. The secondary current vector exceeds the primary current vector δ is positive, and the opposite is negative, and the division (‘) is calculated.
1. The current transformer must be securely installed, and the metal exposed portion of the transformer housing should be reliably grounded.
2. The same set of current transformers should be installed in the same direction to ensure that the positive direction of the current acoustist and the secondary loop current is consistent and easy to observe the nameplate as much as possible.
3. The secondary side of the current transformer is not allowed to open, and only one secondary circuit is used for the secondary double-round transformer, and the other secondary loop should be reliably short.
4, the secondary side of the low voltage current transformer can be connected. Since the wire used by the low pressure metering device, the electric energy table and the insulation level of the transformer are the same, the highest voltage can be affected is substantially consistent; after the secondary winding is grounded, the level of insulation levels in the first circuit of the whole set will decrease, easy to make insulating weaknesses The electric energy meter or transformer is damaged when high voltage effects (such as induced lightning). From the reduction of lightning strike damage, it is also good in the second side.
The above is a description of the correlation between "Current Transformer Common Technical Parameters and Installation Specifications". Introduction to the above, I hope that you can better understand "current transformers".