Current Transformer

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Welcome to Manutech Europe a trusted supplier of Current Transformer & other current Measuring products. Our Current Transformer range offers Split-Core Current Transformers, Solid-Core Sensors, Rogowski Coils, Three Phase Current Sensors products and More. We stock quality Voltage Sensors and effective Power Meters.

Current Transformers detect electric currents in circuits to generate signals proportional to that current. The signals can be displayed, measured or stored for further analysis. Current sensors will measure AC and DC current. While the physical principles are the same, the details of a “current” sensor compared with a voltage transformer will differ owing to different requirements of the application. Shop now and see our wide ranges of current sensing and voltage sensing products.

current transformer

Open & Closed Loop Current Transformers

Current Transformers are of two main types, open or closed loop. The open-loop transformers measure AC and DC currents and provide electrical isolation between the circuit being measured and the output of the sensor (the primary current is measured without electrical contact with the primary circuit, providing galvanic isolation). Open loop current transformers are usually preferred in battery-powered circuits for their low power needs and small footprint features. Open-loop current transformers are also typically cheaper than closed loop CT’s.

Closed-loop transformers provide electrical isolation and measure AC and DC currents. They ideal for their fast response, low temperature drift and high linearity. The closed-loop sensor current output is relatively immune to electrical noise. Due to its Hall-Effect sensor feeds back an opposing current into a secondary coil, the Closed- Loop sensor is sometimes called a ‘Zero-Flux’ sensor. The secondary coil is wound on the magnetic core to zero the flux produced in the magnetic core by the primary current. When high accuracy is priority, closed-loop sensors are a good choice of sensor.

Open loop current transformers have a Hall sensor mounted in the air gap of a magnetic core. A conductor gives a magnetic field that is comparable to the current. The magnetic field is measured by the Hall sensor and concentrated by the core. The signal from the Hall generator is amplified as it is low, this amplified signal becomes the sensor’s output. Normally open-loop sensors have circuitry that provides temperature compensation and calibrated high-level voltage output. While they are cheaper than their counterparts, they can be prone to saturation and temperature drift. However by injecting a positive coefficient in the control current to reduce the drift in sensitivity over temperature the drift can be minimised.

current transformer

3 Types of CT’s

Hall Effect – Hall Effect current transformer devices have a core, Hall Effect device and signal conditioning circuitry. When the Hall device is exposed to magnetic field from the core it produces a potential difference  which can be measured and amplified. Current transformer work when a current conductor passes through a magnetically permeable core that concentrates the conductors magnetic field. Inductive – This type of sensor uses coils which  current-carrying wires pass. Making power that is proportional to the current flow in the coil. The current flow then can be measured or transformed. Magnetoresistive – The property of certain materials changes the value of its resistance when a current flows through the plate. When currents flow for a longer distance, resistance is increased and decreased at the shorter distance.

A Current transformer generates a proportional signal for measurement and control by detecting electric current in a wire. While the physical principles are the same, the details of a “current” transformer compared with a voltage transformer will differ owing to different requirements of the application. Shop now and see our wide ranges of current sensing and voltage sensing products.

We have been in business for over 30 years supplying big and small amounts of accurate Current measuring products. We promise fast delivery, competitive prices and fulfill orders of any quantity. Subscribe to our mailshot for a 5% discount on your next order and to keep informed with our on sale products!

current transformer

ACT-0140 Split Core Current Transformer

The ACT-0140 was previously known as the MAG-J141C005, which is a split core current transformer for measuring current. The input ratings for this AC current sensor are between 1500 and 2400 Amps. The corresponding output is 5A. The transducer has been manufactured using high quality, durable materials, which are mainly nickel laminations. The device is perfect for installation on an existing electrical wire, as it can simply be snapped around the conductor carrying the current to be measured. It comes with a self-locking mechanism for ease of use. The 0.94 inch opening makes it very easy for the device to be put into place. The ACT-0140 features an accuracy of up to class 0.5/1.0VA. Additionally, its rated voltage is 720V (0.72kV). It can withstand 1.2 times continuous rated current before overload. It operates in a temperature range of between -20 to 70 degrees Celsius.

The test voltage is 3kV for a full minute on a frequency range of between 60 and 60 Hz. The input is 2,400 Amps, which is higher than that for the ACT-0073 split core current transformer, which has an input of up to 1,000 Amps. The device is fully UL registered, as well as being compliant with CE and RoHS. When purchased, it comes with a six foot lead, 18 AWG. Full schematics on how the device works and operates are included on the company’s website. Further details about the features of the product are also included there, as well as part number and rating and the various dimensions in inches.

current transformer

Wireless SCT-200W Split-Core 2.0″ AC Current Transformer

Small Wireless Current Sensor System

The SCT-200W series by Magnelab is a split core AC wireless current transformer designed to transform up to 1500 Amps of AC input current to 0.333 Volt RMS or 1.0 Volt RMS of output. Suitable for installation on existing electrical wiring by snapping around the conductor without additional wires or connections. For safety, this AC transformer comes with a self-locking mechanism. This device is usually used in recording, data logging, energy management, power monitoring and cost allocation.

Each CT within the set has a radio frequency link. These get their power from the measured current, which links up to the PT Unit controller as long as the current is above 5A. For the set, you will receive three split core current sensors, all wireless, as well as one PT Unit controller. This class 2 transformer controller has three individual outputs, which correspond to the amplitude and phase of the three remote CTs. It is possible to DIN rail mount the controller.

Options and Specifications

All Magnelab devices have specific features. Often, as with the SCT-125W wireless current transformer, the differences are small but important. With the SCT-200W, you will find an up to 1,500 Amps rated input, and a 0.333 or 1.0 Volt output. Its linearity accuracy is 1% either way for 10 percent to 130 percent of rated current and the phase shift is less than 1 degree at rated current. The operating and measurement frequency of the SCT-200W is 60 Hz (50 Hz upon request for Europe and other regions) with a range of 10 meters. The controller itself requires either 120 VAC or 240 VAC for power and, on a bare conductor, its maximum voltage is 600 V. The temperature range is between minus 30 and plus 60 degrees Celsius. The SCT-200W is fully UL recognized, as well as being compliant with both CE and RoHS. It comes with a 7 year warranty.

Click here for Installation Guide.


• Linearity accuracy ±1% from 10% – 130% of rated current
• Phase shift < 1 degree (measured at rated current)
• AC current up to 1,500A
• Wireless range 10 meters
• 1.0V or 0.333V output (select when ordering)
• UL pending, CE mark
• SCT-125W System Available (1.25″ opening, 70A-800A)

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