Flexible Rogowski Coils
specifications of Rogowski Coils CTs
Input range : 5A ~ 100KA
Output range: 0 ~ 20mA 0 ~ 5V 0 ~ 10V (as per clients' request)
Accuracy class: 0.5 ~ 1%
frequency : 0 ~ 3MHZ
Flexible Rogowski Coil for Current Monitoring and Protected Circuit .
Rogowski Coils current transformers' technical details:
Type
Input current
Output current of Rogo Coils
Acc. class
Coil length
pls notice
Integrator
Direct output
LS-8200A
200A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
20mV
1.0
0.4m
Or 3m
Integrator output will require: 24V power
LS-8500A
500A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
50mV
LS-81000A
1000A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
1V
LS-82000A
2000A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
2V
LS-83000A
3000A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
3V
LS-84000A
4000A
0 ~ 20mA 0 ~ 5V 0 ~ 10V
4V
Flexible Rogowski Coils CT
Flexible Rogowski Coils current transformer are designed for easy placement
around cable bundle, bus bars and breaker panels.
Rogowski Coils:
Rogowski coil (RC) current sensors are presented here operate on the same principle as coils that were first introduced in 1912 for magnetic field measurements. At that time, the coils could not be used for relay protection because their output power was not sufficient to drive electro-mechanical relays. However, with today's microprocessor-based equipment, RC current sensors are suitable for such applications. Current transformers have traditionally been used for protection and measurement applications, in part because of their ability to produce the high power output needed by electromechanical equipment. Microprocessor-based equipment makes high power output unnecessary. This article presents novel solutions for differential protection of power transformers, busbars, generators, and large motors. The initial projects included differential protection of EAF transformers, which are the first such applications in the U.S. and most likely in the world.
Rogowski Coil Principle of Operation
For comparative analysis of Rogowski coils and iron-core current transformers (CTs), equivalent circuits and vector diagrams for resistive load are shown in Figure 1. The CT is a non-linear element that saturates whenever flux inside the CT core exceeds the saturation level, resulting in distorted and reduced secondary current that may cause relay misoperation. However, CTs cannot saturate immediately upon the fault inception. The time that it takes to begin the CT saturation is called time-to-saturation. Manufacturers use different algorithms to achieve proper relay performance during the CT saturation or design relays to operate prior to the CT saturation. Remanent flux in the CT core can also cause relay misoperation. To reduce remanent flux, gapped-core CTs have been used.