Current Transformer FAQ

What is the difference between DAE's CTs and other CTs?

• Normally, the secondary of regular CT on the market is 5A. The power should be turn off when construction because it install by penetrating the current. Also, the regular CTs are usually large in size and take up large installation space. Therefore, this type CT doesn’t suitable for the measurement of sub-circuit.
• DAE provides two types of CT. One is dedicated CT. The other one is regular split-core CT. For the former one, its secondary are all mA and only used with DAE meters. The significant feature is its small volume and doesn’t take up panel space. For the later one, regular split-core CT, it suites for the renovation construction where can’t shut down the power at random.

Introduction of CT type

• Classification according to installation way: Split-core and Solid-core
  • Solid-core ：The power should be turn off when the project is under construction.
  • Split-core：Just buckle on the current and don't need to turn off the power.

• Classified by different meters：Regular CT, Dedicated CT
  • Regular CT：Secondary are all 5A and 1A. Its usually used with standard equipment or 5A input meters. Regular CTs are usually large in size and in solid-core type.  Regular Split-core CT is rare and relatively expensive. 
  • Dedicated CT：This type of CT is for sepecific meters and can not used with normal meters. Its secondary value is being transform into mA signal for meter calculate. Its measurement range are from Tens of Amps to hundreds of Amps. Small in size, it is very suitable for use in branch circuits or circuits with small capacity. 

Notifications for CT choosing

• Current range：Add 50% more than the estimated maximum current. 
• Cable’s AWG：CT’s inner dimension must larger than cable’s AWG. 
• If the installation is temporary, it will be more useful to choose an open-clamp type CT.

Notifications for CT installation

•  Output for dedicated is mA. Therefore, dedicated CT could be installed even doesn’t turn off power. On the contrary, the power must be turn off when install regular CT. 
• Please notify the phase accuracy when install CT. 
• Please notify the direction of + , -. 
• There must be sufficient current to identify during the test. 
• Since both PT and CT are indirect inductions, it is more difficult to judge the phase sequence matching. At this time, please test several combinations before making a judgment.