What is a class C current transformer?
Classification C or K covers current transformers in which the leakage flux in the core does not have an appreciable effect on the ratio or ratios within the limit of current and burden. K classification shall have a knee-point voltage of at least 70 percent of the secondary terminal voltage rating (IEEE C57.
What is the class of current transformer?
Current transformers are divided up into classes according to their precision. Standard precision classes are 0.1; 0.2; 0.5; 1; 3; 5; 0.1 S; 0.2 S; 0.5 S. The class sign equates to an error curve pertaining to current and angle errors. The precision classes of current transformers are related to the measured value.
What does C200 mean for CT?
The standard CT burden is the load that will result in the rated secondary voltage Vs at 20 x 5A = 100A. So for a C200 CT, the standard burden will be 2 ohms, for a C400, it will be 4 ohms.
What is C400 current transformer?
5L400 (CSA) means 5% allowable error up to 20 times rated current into a 4 ohm burden. C400 (IEEE) means 10% allowable error up to 20 times rated current into a 4 ohm burden.
What is a Class 1 current transformer?
The class designation is an approximate 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% or less. Errors in phase are also important, especially in power measuring circuits.
Is 2705 a current transformer?
3.5 Rated extended primary current shall be 120% of rated primary Current in accordance with IS:2705 Pt-II. 3.6 Rated ISF (Instrument Security Factor) shall be declared by the manufacturer & marked on the CT.
What is class of CT and PT?
The standard accuracy classes of current transformer as per IS-2705 are 0.1, 0.2, 0.5, 1, 3 and 5 for metering CT….Application of CT Core According to Their Class.
| Application | Accuracy Class | |
|---|---|---|
| Precession Metering | 0.1 or 0.2 | BL |
| Commertial Metering | 0.5 or 1.0 | AM, BM, CM |
| Ammeters | 1 or 3 | CD |
| Protection Relays | 5P10 or 5P20 | STU |
What is the class of CT?
What does C400 CT mean?
For example, with 20 times rated current flowing in a B-4.0 burden, if the accuracy limit is met, the secondary terminal voltage would be 400 V and the CT accuracy class is C400. For a limit of error current of 10 percent with 20 times rated current flowing, the error current upper limit would be 10% x 5 A x 20 = 10 A.
What is the difference between 0.2 and 0.2 S Class CT?
0.2 and 0.2S are both indicates the accuracy of current transformer. However, the 0.2S class CT is more accurate than 0.2 class current transformer. 0.2 S class CT gives +/- 0.2 % error when loading on the CT is between 100 to 120 %.
What is IS2705?
IS2705(Partl): 1992. 3.10 Rated Secondary Current. The value of the secondary current which appears in. the designation of the transformer !nd on which the performance of the transformer is based.
What IEC 61869?
IEC 61869-11:2017 is a product standard and covers only additional requirements for low-power passive voltage transformers (passive LPVT). This document covers low-power passive voltage transformers used for measurement or protection and low-power passive voltage transformers used for both measurement and protection.
What are the types of current transformers?
The most common type is the toroidal or donut type which has no internal primary winding as such. The primary is the conductor in which the current is to be monitored. The primary conductor is simply placed through the window of the current transformer. The core in this type is a band of magnetic grade steel concentricly wound upon itself.
What voltage class is a toroidal current transformer?
While a few manufacturers offer toroidal current transformers of the 2.5 and 5.0 KV voltage class, the vast majority of toroidal type current transformers are 600V class.
Can a 15kv transformer be used on a 600V circuit breaker?
Most of the switchgear circuit breaker manufactures design the bushings so they will accept one or more 600V class current transformers even though the breaker is rated 15KV class. This approach is much more cost effective as the cost of a 600V class compared to a 15KV class current transformer is relatively much less.
What is the ratio of primary and secondary turns in transformer?
Therefore, you can take, for example, a 100:5A current transformer, take four primary turns and make it a 25:5A ratio (100/4 = 25), and enjoy the better 100:5A performance characteristics at the 25:5A current ratio. It is possible to make fine adjustments to the current by applying secondary turns to the current transformer.