Hall current sensors, also commonly known as current transformers or CTs, are devices that measure the current flowing through a wire by using a magnetic field to detect the current and produce a proportional output. What are split-core Hall current sensors? They are used with both AC and DC currents. Split-core Hall current sensors allow us to measure current passively without interrupting the circuit in any way. They are placed around the conductor that we want to measure.

Current transformers are essential in many applications. For example, they are commonly used in sub-metering to determine the energy usage of individual tenants. They also help facility management reduce costs and improve efficiency by providing information about energy usage and timing.

How do split-core Hall current sensors work?

When current flows through a conductor, it generates a proportional magnetic field around the conductor. Current transformers use this magnetic field to measure the current. If the CT is designed to measure AC current, inductive technology is typically used. AC current changes potential, causing the magnetic field to continuously collapse and expand. In AC current sensors, the wire is wound around a core. The magnetic field generated by the current through the conductor induces a proportional current or voltage in the wires inside the current sensor. The sensor then outputs a certain voltage or current, which can be read and converted by a meter connected to the sensor to determine the amount of current flowing through the conductor. For example, when the current through the conductor is 400A, a current transformer with an output of 333mV (a common output for CTs) can be used. Once you configure the meter to read 400A when receiving a 333mV input, it will be able to calculate the amperage flowing through the conductor based on the input received. DC current sensors work similarly but rely on Hall effect technology, which is the operating principle behind split-core Hall current sensors.

Current transformers can step up, step down, or keep the current unchanged. Sensors that step up or step down the current are often called transformers. A sensor typically consists of two coils. The coil through which current flows is called the primary winding, and the coil that induces voltage is called the secondary winding. For many current transformers sold on vicorv.com, the conductor where the CT is installed serves as the primary winding, while the secondary winding is inside the transformer. The magnetic core around which the secondary winding is wrapped depends on the design handling of the sensor. The turns ratio of a transformer is the number of turns in the secondary winding divided by the number of turns in the primary winding. This ratio determines whether the transformer steps up or steps down the voltage. The ratio of secondary voltage to primary voltage is equal to the turns ratio, as shown in the equation. Therefore, when the number of turns on the secondary winding is greater than the number of turns on the primary winding, the voltage on the secondary winding is higher, making it a step-up transformer. Current behaves oppositely; the ratio of secondary current to primary current is equal to the inverse of the turns ratio.