Current Transformer


The Current Transformers (Cts) are designed for ease of mounting and access, as well as to minimise space requirements. The standard frames, which include overlapping current ratios, permit selection for any cable or busbar system. Enclosed, Tape Wound and Resin Cast Measurement Cts and Tape Wound and Resin Cast Protection Cts for DIN Rail, Busbar and Bracket Mounting are offered but CTs beyond the range specified in this catalogue, also can be offered on request.

Measurement CTs are required to transform the primary current, at various classes of accuracy, as specified by the class designation, over a current range from 5% to 120% of its rated primary current. The design of this type of CT requires the inclusion of a core and winding which will, when connected to its rated burden, perform within the limits of error as indicated by the standards specifications. It is an advantage for a measurement CT to saturate above this range, which provides a protection against damage to instrument by limiting the secondary current, when surge current or faults appear in the primary circuit.

The Series SCT CTs, i.e. SCT- 1, SCT-2 and SCT-3, from 30/5 Amps to 1200/5 Amps are provided with unique feature of DIN rail mounting facility at the base of the CTs for mounting on DIN35 rails. This feature is a boon to panel manufacturers allowing the CT to be mounted at any location with ease. The DIN rail mounting and other mounting and cabling features make the SCTs the most versatile Current Transformer range.

Series SCT CTs are certified for the following marks.

• Enclosure is made of high Impact flame resistant ABS.
• Terminal cover is clear acrylic for easy visibility. Also sealing arrangement is provided as a standard feature in all sizes.
• Terminals are shrouded when cover is removed and knockouts are provided in the shroud to allow selection of cable entry direction.
• Pleasing grey colour. Cost effective, economical design.
• Primary currents from 30 Amps to 4000 Amps. Secondary currents 1 Amp and 5 Amps
• Available in six frame sizes – SCT-1 to SCT-6 and accuracy classes of 0.5, 1, 3 and 5.
• Option of Terminal Connections – Direct, Cable Clamp or Cable lug.
• Option of mounting arrangements – DIN rail mounting on DIN35 rail, on feet, on bottom and sides, panel and bulkhead.
• Clips are provided for foot mounting as standard for all sizes.
• Busbar Clamps are provided as standard accessories from size SCT-3 onwards.


Series SCT CTs measure currents from 30 Amps to 4000 Amps. Their accuracy allows operation within the range of 5% to 120% of the primary current. This accuracy depends on the load connected to the secondary of the CTs, which includes both the impedance of the connected measuring instruments and connecting cables. The CTs can be mounted in direct contact with the busbars operating at a maximum temperature of 1 05°C. They can withstand, without damage, the high temperatures that can occur in enclosed switchboards.

• Designed to comply with IS 2705 – 1992
• Di-electric strength of 2.50 kV for one minute.
• Nominal frequency 50/60 Hz.
• Rated voltage 660V AC max.
• Short circuit thermal current (lth) – 60 times rated primary current for one sec.
• Rated dynamic current (I Dyn) – 2.5 Times lth
• Degree of protection IP40





Series SCT offers following features:
1.Tamper proof terminal cover.
2.Bus bar clamp.
3.0pen circuit protection feature.
4.Multiple mounting options.
5.Multiple clamping options.

The CTs cover a range from 50 AMP to 2500 AMP and with 1 AMP or 5AMP options on the secondary, with accuracies class of 0.5, 1, 3
and 5 for a wide range of VA ratings.

Conform to IS 2705 1992
Primary current 50 A to 2500 A, Secondary current 5 A or 1A. Maximum voltage 660V. Test voltage 2.50kV, 50Hz for 1 minute. Thermal current 60 In, Dynamic current 150 In
Flame resistant, high impact ABS plastic case, sealable terminal covers, Bulk head mounting bracket and busbar clamps provided as standard accessories. Available from 50/ SA to 2500/SA in 3 sizes

Suitable for bus bars 31.5mm x 6.30mm or 32mm dia range from 50/SA to 150/5A.

Suitable for bus bars 40mm x 12.60mm or 32mm dia. and range from 75/5A to 400/5A.

Suitable for bus bars 80 mm x 25.2 mm or 47mm dia. and range from 300/SA to 2500/5A. For class and VA coverage for each rating of CT please refer the chart in the next page.


• CTS with special Ratio and dimensions excluded from above can be made on request
• Due to constant imprOvements in design right is reserved to supply products which may differ slightly in shape from those shown in drawing without affecting limiting dimensions



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