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. 123-9523
Mfr. Part No.4NC5225-0CE20
BrandSiemens
PHP4,234.02
Each
units
400:1 28mm Window - - 400A 1 A - -10°C - 55°C - 80 x 64 x 85.5 mm Measuring Devices
RS Stock No. 772-1221
Mfr. Part No.5SV8702-0KK
BrandSiemens
PHP10,897.00
Each
units
- 35mm Toroidal Ring - - - - 79mm -10°C 100mm +50°C 58.8mm - -
RS Stock No. 123-9507
Mfr. Part No.4NC5115-0BC20
BrandSiemens
PHP5,483.56
Each
units
75:1 17.5mm Window - - 75A 1 A - -10°C - 55°C - 74.5 x 48 x 80 mm Measuring Devices
RS Stock No. 510-9152
Mfr. Part No.7KT1201
BrandSiemens
PHP5,680.37
Each
units
- 13mm Straight Through - - - - - - - - - - -
RS Stock No. 772-1212
Mfr. Part No.5SV8700-0KK
BrandSiemens
PHP7,534.50
Each
units
- 20mm Toroidal Ring - - - - 34mm -10°C - +50°C - - -
RS Stock No. 175-6200
Mfr. Part No.4NC5432-0DH21
BrandSiemens
PHP8,223.52
Each
units
1000:1 - Window - - 1000A 1 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. 175-6204
Mfr. Part No.4NC5433-2DH21
BrandSiemens
PHP7,732.13
Each
units
1200:5 - Window - - 1200A 5 A 84.1mm -30°C 112mm +55°C 127.5mm 112 x 127.5 x 84.1 mm Sentron Power Monitoring Devices
New
RS Stock No. 216-4358
Mfr. Part No.3RB2966-2WH2
BrandSiemens
PHP29,347.73
Each
units
63 - 630 - Straight Through - - - - 147mm - 145mm - - - -
RS Stock No. 175-6154
Mfr. Part No.4NC5123-2FC21
BrandSiemens
PHP4,343.23
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
New
RS Stock No. 213-1330
Mfr. Part No.5SV8704-0KK
BrandSiemens
PHP18,312.64
Each
units
- - - - - 250A 100 mA 33mm - 170mm - - - -
RS Stock No. 175-6210
Mfr. Part No.4NC5435-2CH21
BrandSiemens
PHP5,645.87
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. 175-6143
Mfr. Part No.4NC5121-2DC21
BrandSiemens
PHP3,697.79
Each
units
150:1 - Window - - 150A 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. 175-6128
Mfr. Part No.3UL2900
BrandSiemens
PHP301.16
Each
units
- - - - - - - 54mm -25°C 9.2mm +60°C 18.3mm 9.2 x 18.3 x 54 mm 3UL23 Residual Current Transformers
RS Stock No. 175-6218
Mfr. Part No.4NC5440-2DM21
BrandSiemens
PHP7,651.18
Each
units
2500:5 - Window - - 2500A 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. 175-6135
Mfr. Part No.4NC5117-0CC21
BrandSiemens
PHP4,915.43
Each
units
100:1 - Window - - 100A 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. 175-6132
Mfr. Part No.4NC5113-2CB21
BrandSiemens
PHP3,929.01
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
RS Stock No. 175-6131
Mfr. Part No.4NC5113-0CB21
BrandSiemens
PHP4,819.05
Each
units
60:1 - Window - - 60A 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. 175-6139
Mfr. Part No.4NC5117-2DA21
BrandSiemens
PHP4,544.25
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. 123-9515
Mfr. Part No.4NC5123-0CE20
BrandSiemens
PHP3,501.59
Each
units
250:1 17.5mm Window - - 250A 1 A - -10°C - 55°C - 74.5 x 48 x 80 mm Measuring Devices
New
RS Stock No. 213-1329
Mfr. Part No.5SV8703-0KK
BrandSiemens
PHP12,715.19
Each
units
- - - - - 200A 30 mA 33mm - 130mm - - - -