HY-ZCT-09 Type Zero-sequence Current Transformer


The HY-ZCT-09 type zero-sequence current transformer is used in conjunction with the relay protection device or signal when the power system generates zero-sequence grounding current to make the device components act and realize protection or monitoring.

When an electric shock or leakage fault occurs in the circuit, the secondary side of the transformer outputs the zero-sequence current, so that the equipment on the connected secondary line can be protected (cut off the power supply, alarm, etc.).


  • Detection of unbalanced current: ZCT is designed to measure the unbalanced current in a three-phase electrical system, which is the sum of the three phase currents. This allows them to detect ground faults, which can occur when a fault current flows from one or more of the phase conductors to ground.
  • High sensitivity: ZCT is highly sensitive and can detect even small amounts of ground fault current. This helps to prevent damage to equipment and reduce the risk of electric shock to personnel.
  • Accuracy: ZCT is designed to provide accurate measurements of the zero-sequence component of the current, even in the presence of high levels of noise or interference.
  • Non-intrusive installation: ZCT is typically installed around the neutral conductor of a three-phase system, which means that they can be installed without the need to break the circuit or interrupt power to the load.
  • Frequency response: ZCT is designed to operate over a wide range of frequencies, typically from 50Hz to 400Hz, which makes them suitable for use in a variety of applications.
  • Low burden: ZCT is designed to have a low burden, which means that they do not significantly affect the operation of the circuit or the accuracy of other measurement devices in the system.


  • Widely applied to relaying protection field;
  • Adoption of ABS flame-retardant plastic shell;
  • Epoxy resin casting encapsulation, strong insulation and isolation capability, moisture proof and seismic resistance;

The Difference Between Current Transformer and Zero Sequence Current Transformer?

Current transformers (CTs) are electrical devices used to measure electrical current in a circuit. They work on the principle of electromagnetic induction and are commonly used in power systems to measure high currents.

A current transformer (CT) is used to measure the current in a single phase or three-phase circuit. It has a primary winding that is connected in series with the circuit carrying the current to be measured, and a secondary winding that is connected to the measuring device. The secondary winding produces a current that is proportional to the current in the primary winding.

On the other hand, a zero sequence current transformer (ZCT) is a special type of current transformer that is used to measure the sum of the currents in all the phases of a three-phase system. It is designed to detect the flow of zero-sequence current, which is the current that flows in the neutral conductor of a three-phase system when the three phase currents are unbalanced.

A ZCT is used to detect ground faults in three-phase systems. It measures the zero-sequence current in the system and provides a signal to the protective relay when the current exceeds a preset threshold. The protective relay then trips the circuit breaker to isolate the fault and protect the system from damage.

In summary, the main difference between a current transformer and a zero sequence current transformer is that the former is used to measure the current in a single phase or three-phase circuit, while the latter is used to measure the zero-sequence current in a three-phase system to detect ground faults.

Model First Current Secondary Current
HY-ZCT-09 10-400mA 6-500mV
Model First Current Secondary Current
HY-ZCT-09 10-400mA 6-500mV


HY-ZCT-09 Type Zero-sequence Current Transformer-heyi

    contact us

    24Hs online service   365Ds NON-Stop Production   20Ys Professional Manufacturers Professional designer and manufacturer of current transformer,cooperated with Siemens ,schneider Fuji electrical softbank LG samdsung.
    Company HEYI Electrical CO.,LTD Contact person Bethy
    Tel 86-13968747975 E-mail bethy@heyiele.com
    ADD Xinguang Ind.Zone, Liushi Town, Wenzhou, Zhejiang, China


    Register as one of our members and provide you with the latest product and discount information.