CT & PT Testing
Comparison - CT PT Analyzer & CT PT Pro
Video - CT/PT Analyzer
Theory - CT/PT Testing
Frequently Asked Questions ( FAQ )
CT (Current Transformer) – Theory
Like any other transformer, a current transformer has a primary winding, a magnetic core, and a secondary winding. The alternating current flowing in the primary produces an alternating magnetic field in the core, which then induces an alternating current in the secondary winding circuit. An essential objective of current transformer design is to ensure that the primary and secondary circuits are efficiently coupled, so that the secondary current bears an accurate relationship to the primary current.
PT (Potential Transformer) – Theory
A Voltage Transformer theory or Potential Transformer theory is just like theory of general purpose step down transformer. Primary of this transformer is connected across the phases or and ground depending upon the requirement. Just like the transformer, used for stepping down purpose, potential transformer i.e. PT has lower turns winding at its secondary. The system voltage is applied across the terminals of primary winding of that transformer, and then proportionate secondary voltage appears across the secondary terminals of the PT.
Below is the list of Major tests conducted on CT & PT
Insulation Resistance Test
Secondary/Loop Resistance Test
Burden Test (optional test)
Magnetization Curve Test (optional test)
Hysteresis Curve Test
Turns Ratio Test (optional test)
Primary Injection Test
High Voltage Test
CT PT Analyzer
Which type of CT’s can be tested by KPM CT PT Analyzer ?
KPM CT PT Analyzer is capable of testing nearly all type of CT and PT which includes Metering as well as protection CTs . In terms of applications all type of CTs used in power distribution , transmission and generation can be tested using KPM CT / PT Analyzer . Special application CTs such as bus duct ring CT , Transformer Bushing CT can also be tester .
Can KPM CT PT Analyzer test Generator Bus Duct CTs ?
Yes KPM CT PT analyzer can test Generator Bus Duct CTs with perfection .
Can KPM CT PT Analyzer test Power Transformer Bushing CTs ?
Yes , KPM CT PT Analyzer test Power Transformer Bushing CTs with perfection .
Why Testing a Power Transformer Bushing CT is a complex affair for any CT Testing Equipment ?
KPM CT PT Analyzer works on the principle of Voltage Ratio Method . While testing a Power Transformer Bushing CT, the primary circuit is connected to Power Transformer Winding in series which makes the testing complex .
What is the highest knee point tested by KPM CT PT Analyzer .
KPM CT PT Analyzer saturates the core of CTs with high knee point using reducing frequency principle . So practically it can test the knee point of all type of EHV Protection CTs using its low voltage source .
Is KPM CT PT analyser portable ?
KPM CT PT Analyzer is highly portable with Size (WXHXD) in mm 485 X 356 X 183 & Weight < 15Kg. This makes it an ideal equipment to travel with .
Which type of power sector customers are using KPM CT PT Analyzer
KPM CT PT Analyzer is used by all type of customers which are in Generation ,Transmission as well as distribution of energy .
Can we measure primary and secondary resistance of a PT using KPM CT PT analyzer
The primary winding resistance of PT is in Kohms . KPM CT PT Analyzer is having resistance range in Kohms, with the help of which it can easily test primary resistance of a PT . Secondary resistance of PT is in ohms which can be easily tested .
Can we get a hysteresis curve of a CT using KPM CT PT analyzer
Yes KPM CT PT analyzer is having a hysteresis curve function. By the end of test the Hysteresis curve of CT is calculated which clearly shows the power loss characteristics of the the CT under Test .
What is hysteresis curve and what is its relevance
The magnetization of ferromagnetic substances due to a varying magnetic field lags behind the field. This effect is called hysteresis, and the term is used to describe any system in whose response depends not only on its current state, but also upon its past history.
How KPM CT PT analyzer can automatically find a winding resistance value @75’C.
KPM CT PT analyzer is having onboard temperature sensor with the help of which it measures the room temperature at the time of winding resistance testing, Once testing is complete it shows the winding resistance value at room temperature and also the winding resistance temperature compansated value @ 75'C automatically .
What is CT secondary burden test and what is its relevance
All type of CTs & PTs are designed for a fix burden of load to support . If the connected burden of a CT is more than the required burden then the CT output will not be as per specifications and error will be introduced .
Which test can be conducted using KPM CT PT analyzer ?
Below test can be conducted on CT and PT using KPM CT / PT Analyzer