Appendix Ⅷ Current Transfomer; Ct Type; Ct Cable; Ct Connection On Secondary Side - Sinexcel SVG 100 Ultra User Manual

APPENDIX Ⅷ CURRENT TRANSFOMER
As one of external components of SVG, current transformer (CT) plays a key role in the normal operation of
SVG, so the selection of external CT is extremely important. In 3-phase 3-wire system, two CTs are required,
each installed on phase L1 and phase L3; while in 3-phase 4-wire system, three CTs are required, each
installed on the circuits of phase L1, phase L2 and phase L3.

CT TYPE

SVG can use external CT ratio between 50:5~30000:5. Practical CT ratio should be selected within this range
in accordance with actual load current. The setting of the CT ratio can be programmed into SVG via the
settings during the commissioning phase.
Split-core or Solid-core CTs are both suitable for use. The accuracy of current transformer should be higher
than 0.2 (Solid-core) or 0.5 (Split-core). Lower degree of accuracy may affect the compensation accuracy.
Caution
Caution

CT CABLE

As an accessory of Sinexcel SVG system, CT cable may contain three groups of shielded twisted pair (STP):
yellow + black, green + black and red + black, each group consisting of two cables, twisted in pair to constitute
CT cable. When the external CT is connected and installed, the yellow twisted pair is connected to phase A,
the green to phase B and the red to phase C. Take the yellow as example, yellow pair is connected to S1 of
external CT1, and the black to S2 of external CT1, ensuring the same direction of current straight through CT.
Otherwise it may fail to achieve effect of compensation.
For CT cable shorter than 15m, recommended sectional area is 2.5mm
sectional area is 4mm 2 . Above 30m, please contact Sinexcel.

CT CONNECTION ON SECONDARY SIDE

When connecting the secondary CT cables to SVG module, for A phase the S1 terminal of the CT is
connected to the CT_A marked terminal on SVG and the S2 terminal of the CT is connected to the
CT_A_GND marked terminal of SVG. This is duplicated for each phase.

CT SIZING

The CT ratio selection should be 1.5~4 times to maximum load current.
Before power on, check if the CT ratio of the external CT is correct
according to the settings in the touch screen. If not, SVG will not
operate correctly.
The CT primary should be selected to be 1.5~4 times (mostly choose 2
times)of the actual load current. Too small may result in equipment
alarm; too large may affect the compensation performance. If special
needs, please contact Sinexcel.
2 . From 15m to 30m, recommended
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