Current Transformer - Page 1
Forum section: electronics / projects

author: EEVaditya
author_rank: Regular Contributor
timestamp: September 07, 2015, 03:32:19 pm
content: Hello,I am looking for Transformer with following details marked on it:50~60Hz660V300/5AI am unable to understand other written things as those are not in English Language(Please see the attached image)

author: mij59
author_rank: Frequent Contributor
timestamp: September 07, 2015, 03:45:30 pm
content: From the first picture:Current transformation ratio 300A to 5A.Nominal power 5 VA.Nominal voltage 660VAccuracy 0.5%

author: Gyro
author_rank: Super Contributor
timestamp: September 07, 2015, 05:31:17 pm
content: The 660V figure will be a 'class' rating rather than an electrical parameter - ie. The center hole is physically large enough to accommodate a 660V rated cable with a capacity of at least 300A.Edit: The insulation will be rated to take a 660V rms uninsulated conductor (buss bar) through the center too.

author: EEVaditya
author_rank: Regular Contributor
timestamp: September 08, 2015, 02:56:44 pm
content: can anyone provide me the technical details or datasheet for the exact part because I saw intensely but I am not getting

author: MagicSmoker
author_rank: Super Contributor
timestamp: September 08, 2015, 03:11:33 pm
content: Quote from: EEVaditya on September 08, 2015, 02:56:44 pmYou are over-thinking this. 50/60Hz current transformers are pretty common so there are lots to choose from. Here is just one example from a reputable online store:http://www.galco.com/buy/Simpson/37023?source=googleshopping&gclid=CK227ubb58cCFc6PHwod2cILEg&kpid=37023-SPSNOtherwise, search for the phrase "current transformer 300/5"; where the "300/5" specifies the transformation ratio.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 09, 2015, 03:03:06 am
content: Quote from: mij59 on September 07, 2015, 03:45:30 pm"Current transformation ratio 300A to 5A."Not unless that transformer is going to step the voltage UP by a factor of 300/5!Every current transformer that I've ever seen measures amperage but gives avoltageoutput. In this case 5 volts AC out when the current through it is 300 Amps. The outputvoltageis directly proportional to thecurrentin the conductor that passes through the center hole. 2 1/2 VAC output for 150 amps, so on and so forth.660V is also not the nominal voltage but the MAXIMUM safe voltage.

author: nctnico
author_rank: Super Contributor
timestamp: September 09, 2015, 03:20:51 am
content: Nope. A current transformer does current in to current out. The output voltage depends on a burden resistor.

author: Circlotron
author_rank: Super Contributor
timestamp: September 09, 2015, 03:32:05 am
content: Quote from: Stray Electron on September 09, 2015, 03:03:06 amNo. The output voltage of a current transformer can go up and up until either the iron saturates or the winding flashes over. CTs are happiest running into a dead short circuit, or in a practical situation, a very low resistance. The output current is directly related to the input current, and seeing the secondary is a current source it will alter it's output voltage to whatever it needs to be to make that exact secondary current flow.

author: mij59
author_rank: Frequent Contributor
timestamp: September 09, 2015, 03:35:53 am
content: Quote from: Stray Electron on September 09, 2015, 03:03:06 amAs the name suggest a current transformer has a fixed current transformation ratio , in this case 300A input gives 5A output.The maximum voltage the current transformer can provide is 1V, its limited by the power rating, in this case 5VA.A current transformer can never be configured as a voltage output, not connecting a load to output of the transformer will generate a very high output voltage causing breakdown of the wire isolation.

author: Circlotron
author_rank: Super Contributor
timestamp: September 09, 2015, 05:52:43 am
content: Quote from: mij59 on September 09, 2015, 03:35:53 amWhile maintaining a given linearity.As you say, it can gointo an open circuit.