Current Transformer (CT) Data

This dialog box includes the following areas and tabs:

See Common Tabs for information on the Location, Reliability, Comments, Hyperlinks, Media Gallery, or Collected Data tabs.

Figure 1: CT Data Dialog Box

Connection Information

Option Description
ID Name

Uniquely identifies the equipment item. The program automatically assigns a name, but you can change it, if needed. The name can be up to 16 characters long.

For current transformers, the program automatically assigns the names CT-1, CT-2, CT-3, and so on.

Conn Relay The relay connected to the current transformer. The ID name of the connected relay is displayed here.
Conn Bus The bus connected to the current transformer. The ID name of the connected bus is displayed here.
Conn Item The item connected to the current transformer. The ID Name of the connected item is displayed here.
Group Name/Type If the CT is part of a functional group, the group name and type appears here. See Functional Groups.

Phase

The phase of the item. Currently, this is for reference only.

CT Specifications Tab

Option Description
CT Function Number of current transformer ratios. You can select either Single Ratio or Multi-Ratio. If you select Multi-Ratio, you also need to enter the CT ratio that has been set.
Connected The connection type. You can select either Wye or Delta.
CT Ratio The ratio of rated primary to rated secondary amps of the current transformer. Specify both ratings in the form: (primary amps) / (secondary amps).
Set CT Ratio

The ratio that has been set in the case of multi-ratio current transformer.

Figure 2: Multi-Ratio Options
No. of CTs The number of current transformers in the group.
One-line Graphics

To select the way the CT symbol appears in the one-line diagram. The available choices are as follows:

  • Positive Sequence
  • Zero Sequence
Show Entire Line

If you select this check box, the current transformer appears connected to the relay with a line. If it is not selected, the entire line is not shown. TO (Relay ID) appears next to the CT symbol as shown below.

Figure 3: Example When Line is Not Shown
Allow CT to be arc flash "Main" to nearest bus When this option is selected, the protective device connected to the CT is treated as Main in arc flash analysis.

Tip: To change polarity on a CT after it has been added to the one-line, hold the SHIFT key and drag the leader line closest to the CT downward. The CT and relay must be slightly offset for this to work.

Other Tabs

See Common Tabs for information on the Location, Reliability, Comments, Hyperlinks, Media Gallery, or Collected Data tabs.

More Information

Database Technical Reference Common Tabs
Media Gallery