FAQs
Class 0.2 and class 0.2S are for measuring current transformers. The biggest difference is that at small loads, class 0.2S has higher measurement accuracy than class 0.2. It is mainly used for occasions where the load variation range is relatively large, and sometimes there is almost no load.
What is 0.2 S class meter? ›
The energy measurement should be true four quadrant type. Class of accuracy of the metering system shall be 0.2s for both active and reactive energy measurement. The accuracy should not drift with time.
What is the difference between 0.5 and 0.5 s class CT? ›
For Current Transformers: Class 0.5s is more accurate when you got low values of current. For class 0.5s and with a current between 1-5% In, you got on class 0.5s a 0.75% error. For class 0.5 and with a current between 0-5% In, you got on class 0.5s a 1.5% error.
What is the main difference between protection class CT and metering class CT? ›
Metering CTs are designed to have a high measuring accuracy of up to around 125% of the rated current for all loads. Protection type CTs are designed to operate smoothly in high current up to around 10-20 times of the rated current under fault conditions.
How do I choose a CT rating? ›
To determine the correct current transformer rating, multiply the full load amperes by a factor of 1.25. This places the full load current above 2/3 full scale on the CT, while allowing sufficient head room to also read overload conditions.
What are the different types of CT classes? ›
KSI Product Range
| RING TYPE MEASURING CURRENT TRANSFORMERS |
|---|
| Primary Current | Secondary Current | Accuracy Class |
|---|
| 50A to 5000A | 1A, 5A Or as per customer requirement | CL-5, CL-3, CL-1, CL-0.5, CL-0.2, CL-0.1, CL-0.5S, CL-0.2S |
Oct 12, 2020
The class designation is the measure of the CT's accuracy. The ratio (primary to secondary current) error of a Class 1 CT is 1% at rated current; the ratio error of a Class 0.5 CT is 0.5% at rated current.
What is the accuracy class of a CT? ›
The five accuracy classifications for metering CTs specified by the IEC standard are 0.1, 0.2, 0.2S, 0.5,0.5S 1, 3 and 5. The accuracy class of a CT indicates the maximum permitted inaccuracy of the CT at the rated primary current and is stated as a percentage of the rated primary current.
What is s in accuracy class? ›
It refers to the accuracy of the meter. A 0.2s meter has a much higher accuracy as below. Since Accuracy depends on the load of the system, IEC/AS have developed different standards to define accuracy under different load conditions, known as “Accuracy Class”
How to choose CT burden? ›
A CT's maximum burden will vary depending on the CT's turns ratio, the desired CT output, and the sensor's current rating. CT burden is commonly expressed in one of two ways: The total impedance of the circuit in ohms (Ω) The total VA (volt-amperes) and PF (power factor) at a specified current/voltage and frequency.
Typical rating factors of CT's are 1.0, 1.25, 1.33, 1.5, 2.0, 3.0, and 4.0. Many times the manufacturer will only list the CT rating factor at 30°C ambient (room temperature).
What is the VA rating of CT? ›
The rated power of the current transformer is the product of the rated load and the square of the secondary rated current and is quoted in VA. Standardised values are 2.5 – 5 – 10 – 15 – 30 VA. It is also permissible to select values over 30 VA according to the application case.
What is the best protection class insurance? ›
An ISO “Public Protection Class” rating of Class 1 is the best and a Class 10 is considered “unprotected.” Insurance providers may reduce the costs of homeowner fire insurance in communities rated as Class 1, 2 and 3 where homeowners located in Class 9 or Class 10 may find difficulty in finding reasonable rates for ...
Why does CT ratio 100/5 mean? ›
A 100/5 ratio CT means that the primary current is 20 times greater than the secondary current. When 100 amps is flowing in the primary conductor, it will result in 5 amps flowing in the secondary winding.
What is CT class for protection? ›
Standard classes for protection CT's are 5P 10 and 10P 10, where P is the designation for protection. The number before P indicates the composite error percentage.
What does CT class mean? ›
CT Class Rating is a letter that designates the application for which the CT is rated. Metering CTs are designated with the letter B. Relaying CTs have several different letter designations: C: The CT has low leakage flux. (Accuracy can be calculated before manufacturing.)
What are the classes of CT burden? ›
Typical burden ratings for IEC CTs are 1.5 VA, 3 VA, 5 VA, 10 VA, 15 VA, 20 VA, 30 VA, 45 VA and 60 VA. ANSI/IEEE burden ratings are B-0.1, B-0.2, B-0.5, B-1.0, B-2.0 and B-4.0. This means a CT with a burden rating of B-0.2 will maintain its stated accuracy with up to 0.2 Ω on the secondary circuit.
What are the standard CT ratings? ›
Typical rating factors of CT's are 1.0, 1.25, 1.33, 1.5, 2.0, 3.0, and 4.0. Many times the manufacturer will only list the CT rating factor at 30°C ambient (room temperature).
