Current Transformers

Current transformers or (CT’s) are instruments that are used to transform the current from a high current into a lower current so that the power can then be used for measuring and controlling. The transformers consist of a core, a primary and a secondary winding.RS Components offer an extensive range of highly accurate CT’s in various transformer types, current ratings, CT ratio supply voltages and mounting types to suit every application. Supplied by industry-leading brands including Siemens, Murata Power Solutions LEM and of course RS PRO.

How does a current transformer work?

When an alternating current flows through the primary winding, a magnetic flux is created which then induces an alternating current in the secondary winding. This alternating current is proportional to the current in its primary. Current transformers are also known as a "step-down transformers". Once the current has been reduced it can be safely monitored and measured using an ammeter.

Types of current transformer

Toroidal Current Transformer - These transformers are shaped like a doughnut they do not contain a primary winding. Instead, the line that carries the current flowing in the network is threaded through a window or hole in the toroidal transformer. Toroidal transformers offer high efficiency with minimal excess noise and little excess leakage inductance.Wound Current Transformer The transformers primary winding is physically connected in series with the conductor that carries the measured current flowing in the circuit. The magnitude of the secondary current is dependent on the turns ratio of the transformer.Bar-type Current Transformer – This type of current transformer uses the actual cable or bus-bar of the main circuit as the primary winding, which is equivalent to a single turn. They are fully insulated from the high operating voltage of the system and are usually bolted to the current-carrying device.

Where would I use a current transformer?

CT's are used in a wide range of industrial and commercial measurement applications. Some of the most common are:Generating stationsElectrical substationsCommercial electric power distributionElectrical panels


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Description Price Current Ratio Bore Size Transformer Type Sensor Technology Supply Voltage Input Current Output Current Overall Height Minimum Temperature Overall Width Maximum Temperature Overall Depth Dimensions For Use With
RS Stock No. 175-6154
Mfr. Part No.4NC5123-2FC21
BrandSiemens
TWD2,858.00
Each
units
250:5 - Window - - 250A 5 A 65.6mm -30°C 60mm +55°C 75.3mm 60 x 75.3 x 65.6 mm Sentron Power Monitoring Devices
RS Stock No. 772-1221
Mfr. Part No.5SV8702-0KK
BrandSiemens
TWD7,014.00
Each
units
- 35mm Toroidal Ring - - - - 79mm -10°C 100mm +50°C 58.8mm - -
RS Stock No. 175-6220
Mfr. Part No.4NC5441-2DN21
BrandSiemens
TWD4,805.00
Each
units
3000:5 - Window - - 3000A 5 A 84.1mm -30°C 112mm +55°C 127.5mm 112 x 127.5 x 84.1 mm Sentron Power Monitoring Devices
RS Stock No. 175-6171
Mfr. Part No.4NC5225-0DE21
BrandSiemens
TWD2,225.00
Each
units
400:1 - Window - - 400A 1 A 67.6mm -30°C 60.6mm +55°C 78.4mm 60.6 x 78.4 x 67.6 mm Sentron Power Monitoring Devices
RS Stock No. 175-6160
Mfr. Part No.4NC5222-2CE21
BrandSiemens
TWD1,872.00
Each
units
200:5 - Window - - 200A 5 A 67.6mm -30°C 60.6mm +55°C 78.4mm 60.6 x 78.4 x 67.6 mm Sentron Power Monitoring Devices
RS Stock No. 175-6155
Mfr. Part No.4NC5124-2FE21
BrandSiemens
TWD2,220.00
Each
units
300:5 - Window - - 300A 5 A 65.6mm -30°C 60mm +55°C 75.3mm 60 x 75.3 x 65.6 mm Sentron Power Monitoring Devices
RS Stock No. 175-6225
Mfr. Part No.4NC5940-5LT21
BrandSiemens
TWD160.00
Each
units
- - - - - - - - - - - - - 4NC54 Current Transformers
RS Stock No. 175-6182
Mfr. Part No.4NC5326-0CE21
BrandSiemens
TWD3,282.00
Each
units
500:1 - Window - - 500A 1 A 84.1mm -30°C 82.5mm +55°C 98mm 82.5 x 98 x 84.1 mm Sentron Power Monitoring Devices
RS Stock No. 175-6176
Mfr. Part No.4NC5231-2FE21
BrandSiemens
TWD3,030.00
Each
units
800:5 - Window - - 800A 5 A 62.2mm -30°C 59.5mm +55°C 75.3mm 59.5 x 75.3 x 62.2 mm Sentron Power Monitoring Devices
RS Stock No. 175-6138
Mfr. Part No.4NC5117-2CC21
BrandSiemens
TWD2,585.00
Each
units
100:5 - Window - - 100A 5 A 65.6mm -30°C 60mm +55°C 75.3mm 60 x 75.3 x 65.6 mm Sentron Power Monitoring Devices
RS Stock No. 175-6222
Mfr. Part No.4NC5923-5LT21
BrandSiemens
TWD144.00
Each
units
- - - - - - - - - - - - - 4NC51 Current Transformers
RS Stock No. 123-9505
Mfr. Part No.4NC5113-0BC20
BrandSiemens
TWD4,074.00
Each
units
60:1 17.5mm Window - - 60A 1 A - -10°C - 55°C - 74.5 x 48 x 80 mm Measuring Devices
New
RS Stock No. 210-3465
Mfr. Part No.3RB2906-2JG1
BrandSiemens
TWD6,653.00
Each
units
10 - 100A - Straight Through - - - - 94.1mm - 54.8mm - - - -
RS Stock No. 175-6161
Mfr. Part No.4NC5222-2DE21
BrandSiemens
TWD1,708.00
Each
units
200:5 - Window - - 200A 5 A 67.6mm -30°C 60.6mm +55°C 78.4mm 60.6 x 78.4 x 67.6 mm Sentron Power Monitoring Devices
RS Stock No. 175-6211
Mfr. Part No.4NC5435-2DH21
BrandSiemens
TWD2,564.00
Each
units
1500:5 - Window - - 1500A 5 A 84.1mm -30°C 112mm +55°C 127.5mm 112 x 127.5 x 84.1 mm Sentron Power Monitoring Devices
RS Stock No. 175-6127
Mfr. Part No.3UL2307-1A
BrandSiemens
TWD19,476.00
Each
units
40:1 - Toroidal Ring - - 40A 630 A 62mm -25°C 300mm +60°C 286.2mm 300 x 286.2 x 62 mm Fault Current Monitoring
RS Stock No. 175-6151
Mfr. Part No.4NC5123-0DE21
BrandSiemens
TWD2,195.00
Each
units
250:1 - Window - - 250A 1 A 65.6mm -30°C 60mm +55°C 75.3mm 60 x 75.3 x 65.6 mm Sentron Power Monitoring Devices
RS Stock No. 203-2084
Mfr. Part No.3RB2906-2BG1
BrandSiemens
TWD6,413.00
Each
units
3:1 - Straight Through - - 3A 3 A 83mm - 45.3mm - - - -
New
RS Stock No. 216-4358
Mfr. Part No.3RB2966-2WH2
BrandSiemens
TWD16,982.00
Each
units
63 - 630 - Straight Through - - - - 147mm - 145mm - - - -
RS Stock No. 175-6132
Mfr. Part No.4NC5113-2CB21
BrandSiemens
TWD2,585.00
Each
units
60:5 - Window - - 60A 5 A 65.6mm -30°C 60mm +55°C 75.3mm 60 x 75.3 x 65.6 mm Sentron Power Monitoring Devices