On-Line Capacitive Equipment Insulation Tester

The MOEORW-W4708C online insulation tester for capacitive equipment features a completely new design that overcomes the shortcomings of existing live-line testing systems, offering a variety of testing functions. It can perform online or offline measurements of dielectric loss and capacitance in capacitive equipment. It is primarily used for real-time online monitoring of parameters such as capacitance, dielectric loss, and end-screen current of operating transformer bushings, current transformers (CTs), current transformers (CVTs), and coupling capacitors to determine the insulation status of the equipment.

Overall Machine Parameters

 Measurement range and accuracy

Other characteristics

1.The online insulation tester for capacitive equipment uses a high-precision external through-hole current sensor to replace the previously used "sampling protection unit" (which contains multiple switching circuits used to switch the end-screen current to the test instrument during testing, posing a risk of end-screen open circuit and requiring the operation of multiple shorting tabs to introduce the end-screen current into the test instrument). This sensor has a through-hole structure, allowing it to be installed near the equipment. The end-screen lead has no breaks and the lead distance is very short, fundamentally avoiding safety hazards such as end-screen open circuit. This sensor can accurately detect input signals in the range of 100 μA to 800 mA . The sensor has low input impedance and can withstand 10A power frequency current and 10kA lightning current, meeting the requirements for online testing.
2.The sensor features a die-cast aluminum shell for sealing and waterproofing, and the secondary output uses a waterproof cable connector for easy testing and connection. After the sensor is installed, testing can be performed simply by connecting the secondary cable, achieving "plug and play" functionality without requiring any operation on the signal leads of the end screen.
3.The core processor in the testing instrument employs a real-time embedded operating system and utilizes an external 16-bit, high-speed, multi-channel synchronous sampling analog-to-digital converter (A/D) to achieve real-time measurement and high-precision calculation of monitored quantities. It has the capability to monitor multiple devices simultaneously.
4.Two online dielectric loss detection methods are provided : one can measure the difference in dielectric loss and the ratio of capacitance between two in-phase capacitor-type devices, and the other can use the secondary voltage of the PT as a reference signal to measure the capacitance and dielectric loss values of the devices. Employing a self-compensating high-precision current sensor and advanced digital filtering technology, the accuracy and stability issues of dielectric loss testing are effectively resolved. Combined with comprehensive electromagnetic shielding measures and advanced digital filtering processing technology, the dielectric loss test results are ensured to be unaffected by harmonic interference and pulse interference.
5.The addition of detection functions for dielectric loss difference and capacitance ratio of in-phase capacitor-type equipment not only avoids distortion of dielectric loss test results caused by using the secondary voltage of the PT as a reference signal, but also helps to reduce the influence of interphase electric field interference.
6.The detector is equipped with a 7-inch LCD and capacitive touch screen, which is used to display monitoring data and can show the monitored voltage, current, dielectric loss, capacitance ratio and other data in the form of trend graphs;
7.The tester not only has the function of online real-time detection, but also can perform long-term continuous online monitoring of equipment and automatically record the monitored data.
8.It offers two resistive current detection methods : it can use the secondary side voltage of the PT or the leakage current of the in-phase capacitor-type equipment, and can accurately measure various parameters such as voltage, current, and dielectric loss.
9.This system uses external sensors to replace the "sampling protection unit," allowing for easy upgrades from "live detection" to "online monitoring" while the equipment is running normally. The upgrade requires no removal of the existing sensors or a power outage; only the addition of an IED (Integrated Electronic Device) is needed.
10.The detector adopts a portable design, is lightweight, easy to operate, and uses a high-capacity lithium battery, which fully meets the requirements of field use.

Online monitoring of high-voltage equipment in substations
It is suitable for live-line detection and long-term online monitoring of the insulation status of capacitive equipment under uninterrupted power supply conditions in substations.
 

Insulation Diagnosis of Capacitive Equipment
Used for online measurement of dielectric loss, capacitance, and end-screen current of transformer bushings, CTs, CVTs, and coupling capacitors .
 

Preventive testing of electrical equipment
It replaces traditional power outage pre-testing, enabling regular inspections, data comparison, early warning of defects , and extending the power outage cycle.
 

Portable rapid testing on site
It meets the requirements of single-person on-site operation and plug-and-play functionality , making it suitable for rapid testing and data export in harsh outdoor environments.