Current transducers allow the measurement of current flows with galvanic isolation. They reduce the high voltage currents to a much lower value. The conductor with the measured current must be guided through the loop of the sensor because current transducers function on the principle of a transformer, which means they have a current output signal and this low current signal can then be measured with the DAQ.
Zero-flux current transducers are not simple transformers, they also have sophisticated constructions and integrated electronics. They have two windings which are operated in saturation to measure the DC current, one winding for the AC current and an additional winding for compensation. This kind of current measurement is very precise because of the zero-flux compensation.
This is a very important point because the magnetic core of the transformer stays magnetized with the residual magnetic flux, which destroys the accuracy of the measurement. In these transducers, the parasitic flux is perfectly compensated. Therefore, zero-flux current transducers are used for measuring currents with high precision, but they are not suitable for simple and fast measurement like iron-core clamps or Rogowski coils.
Zero-flux transducers are used to measure currents with the highest accuracy for both AC and DC and have high bandwidth capabilities (up to 1 MHz). They are very linear and have low phase and offset errors.
Connecting a zero-flux transducer to a Sirius system
This chapter explains how to connect zero-flux transducers to a Sirius system. The connection of the zero-flux transducers is illustrated by means of IT 400-S transducers.
Required components for the set up
Firstly connect the zero-flux transducer IT 400-S with the D9m-D9f-5M-MCTS cable to the SIRIUSi-PWR-MCTS slice at the Sensor 1 input.
The D9m-D9f-5M-MCTS cable is a simple extension cable and can be used for all zero-flux transducers (60A up to 1000A).
Take the DSI-MCTS-400-03M cable and use Output 1 of the SIRIUSi-PWR-MCTS to connect it to the first LV input of the Sirius PWR amplifier.
Note: The DSI-MCTS-XXX cable can only be used for certain zero-flux transducers. The cables have a build-in shunts which only correspond to certain transducers. Please refer to the following table for information on.
Repeat Step 1 and 2 for all zero-flux transducers that need to be connect to the system.
A three-phase star system configuration will resemble the image below:
You will find how to connect voltage and current transducers to the system for different wiring configurations (DC, 1-phase, 2-phase, 3-phase delta-star-aron-V, etc.) in the Dewesoft PRO training course “POWER ANALYSIS”
In the DSI-MCTS-XXX cable there is a TEDS chip integrated, where data about scaling, calibration etc. of the zero-flux transducer is stored. If you connect this shunt cable to the Low-Voltage input of the Sirius amplifier all these configurations are done automatically. Therefore the MSI adapters and TEDS sensors have to be activated. Please check at “Settings” – “Settings” if this option is enabled, see screenshot below.
After connecting the sensor (e.g. MCTS 400) you will see in the column Ampl.name the current transducer (e.g. DSI-MCTS-400) and the type of measurement will be changed to “Current”.
Finally you just have to set a suitable measurement range and set a low-pass filter if necessary.