XHXC110 Power Transformer & Current Transformer Demagnetizer
The XHXC110 is a dedicated device designed to eliminate residual magnetism hazards in large power transformers and current transformers after DC resistance testing. It plays a critical role in protecting these equipment from inrush current impacts and ensuring safe commissioning.
Due to the inherent hysteresis of ferromagnetic materials, residual magnetism remains in the iron core after operations such as turns ratio measurement and DC resistance testing of power transformers. This residual magnetism causes half-cycle saturation of the iron core when the transformer is put into operation, generating substantial harmonics in the excitation current. This not only increases the transformer’s reactive power consumption but may also trigger misoperation of relay protectors, leading to economic losses. Therefore, demagnetization must be performed before transformer commissioning to guarantee safe and normal operation.
Building on the original product series, the XHXC110 features an added automatic demagnetization mode, eliminating the need for repeated user operations. The liquid crystal module has been enlarged to display richer information, and it adopts a two-button operation design: a red button for selection and reset, and a green button for confirmation and start-up, ensuring easier operation. The demagnetization time has been reduced from the original 30 minutes to less than 4 minutes.
Hazards of Residual Magnetism
- Triggers misoperation of transformer relay protection devices, leading to repeated failures in transformer commissioning;
- Causes voltage surges when short-circuit faults at transformer outgoing lines are cleared, inducing misoperation of transformer protection and resulting in a total power outage of loads on all sides of the transformer;
- Inrush current generated when an unloaded transformer at Substation A is connected to the power supply induces "sympathetic inrush" in operating transformers at adjacent Substations B and C, causing mis-tripping and large-scale power outages;
- Inrush current may damage transformers and circuit breakers due to excessive electric power;
- Induces switching overvoltage, damaging electrical equipment;
- DC components in inrush current cause over-magnetization of current transformer magnetic circuits, significantly reducing measurement accuracy and the correct operation rate of relay protection devices;
- A large number of harmonics in inrush current severely pollute the power quality of the power grid;
- Causes sudden rises or drops in grid voltage, affecting the normal operation of other electrical equipment.
Performance Characteristics:
* Employs patented technology – DC frequency conversion attenuation principle;
* Three-phase transformers achieve demagnetization by demagnetizing only phase B;
* Features automatic current stabilization judgment and 16-bit AD data acquisition and processing;
* Offers manual/automatic demagnetization modes;
* Fast demagnetization speed – reduced from 30 minutes to no more than 4 minutes per cycle;
* Significant demagnetization effect – increased from 80% to over 90% per cycle;
* Can directly utilize the current line of DC resistance testing, facilitating integration with DC resistance testing;
* Uses a clear Chinese interface with real-time display of demagnetization progress;
* Suitable for eliminating residual magnetism in large power transformers and instrument transformers of 35kV and above before commissioning; especially suitable for large-capacity transformers with voltage levels of 330kV and above;
* This product is small in size and lightweight, making it ideal for field use.
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