They are used to measure alternate currents at 50-60 Hz, up to 600 Arms.
They are based on toroidal Silicon Iron core; they tipically have a high number of secondary turns, so that the secondary current is relatively low. By connecting a burden resistance to the secondary side, you can read a proportional voltage signal, isolated from the mains. As the secondary current is low, the low power burden resistance can be connected to the PCB.
Depending on the size, and in particular on the central hole for passing through cable (or copper bar), there are four current transformer families, called 150, 151, 152 and 153, with pins or faston connection.
Typical working temperature is from -40 to +70°C.
The plastic material of the case is UL94-V0. Main features of mains frequency current transformers are the following ones.
- n secondary to primary turns ratio, that is the number of secondary turns
- RS secondary winding's resistance
- Ip rated primary current (rms value)
- IS rated secondary current (rms value)
- fn optimum working frequency (o optimum working frequency range)
- RC rated burden resistance
- UOUT output voltage at the rated primary current and with rated burden resistance
- E measurement's accuracy at the rated primary current and with rated burden resistance
- Uis maximum working voltage primary/secondary
- Up isolation voltage primary/secondary