Ct Va Burden; Instruction; Mechanical Structure; Ct Ratio - Sinexcel SVG 100 Ultra User Manual

CT VA BURDEN

INSTRUCTION

Current transformers (CT) are used for measuring current, and play a key role in the normal operation of
Sinexcel Static Var Generator.
CT maintains an accurate ratio between the currents in its primary and secondary circuits over a defined
range. The alternating current in the primary produces an alternating magnetic field in the core, which then
induces an alternating current in the secondary.
CTs are specified by a specific current ratio from primary to secondary side. The rated secondary current is
normally 1 or 5A. Sinexcel SVG is compatible with CTs with secondary side current of 1A or 5A.

MECHANICAL STRUCTURE

There are two main types of CTs.
Solid core CTs form a permanently enclosed core. Installing a solid-core CT requires disconnecting the wire
to get it through the CT core. The benefit is that they are usually less expensive and can be more accurate.
They are most often used for new installations.
Split-core CTs have an "opening" in the core that allows the CT to be opened and placed around the
conductor without interrupting the wiring. Split-core CTs can be more expensive, but more convenient.

CT RATIO

Sinexcel SVG is compatible with CTs with secondary side current of 1A or 5A.
For the CT with secondary side current of 1A, the range of CT ratio Sinexcel SVG can support is10/1~6000/1.
For the CT with secondary side current of 5A, the range of CT ratio Sinexcel SVG can support
is50/1~30000/1.

CT BURDEN

CT burden is the total resistance of the secondary side. The maximum CT burden will vary depending on the
CT turns ratio, the desired CT output and the rated current of the sensor. The value of CT burden is given in
the specification of CT.
CT burden is commonly expressed in one of two ways:
The total impedance (Ω)
The total VA

CT CABLE

When choosing the length of CT cable, it's need to consider the following factors
The total resistance of CT's secondary side (CT burden) (check CT spec)
The resistance of CT cable (Calculate based on the cable diameter)
The resistance between the 2 pins of SVG CT port (Sinexcel SVG/SVG is 4.3×10 3VA)
When the total resistance of the two CT cables exceeds the CT burden, the accuracy of the CT will be
reduced. The load on the conductor can be calculated by using the following formula to determine how far the
conductor can be extended without affecting accuracy.
88