PTR Hartmann

Chokes with different core materials

PTR HARTMANN inductive components offer chokes based on iron powder cores. They are suitable for use in various applications where a scattering field resistant design is indispensable. Iron powder cores are formed by compressing powder particles, which are individually insulated to reduce eddy current losses.

Due to these distributed air gaps in the iron powder material of the core, our iron-powder-based chokes manifest only a small dependence on the inductance of the DC bias and this with simultaneous usability of the high saturation induction of iron. We provide optimised iron powder core materials for various applications. Use of iron powder materials to suppress radio interference gives rise to pronounced amplitude permeability and high saturation induction due to the alternating field modulation of the iron powder. The permeability increases with the AC-field strength and reaches a higher effective inductance at operating load than when idle. Chokes with iron powder cores are therefore particularly suitable as attenuators of symmetrical interference voltages in power supply lines, as well as commutation reactors, current limiting inductors and filter chokes.

The low performance of the material ensures good damping of overshoots, as required in such applications as dimmer chokes, filter chokes and commutation reactors. Due to the low permeability drop when implemented in DC applications, iron powder material may also be used in storage chokes. The switching frequency and the maximum change component in the useful signal are decisive for the right choice of core material to optimise specific applications. PTR HARTMANNs iron-powder-based chokes are offered in toroidal and EF-core versions that conform to DIN EN 60938-2.

All materials used are UL tested. If desired, an assembly using our UL insulation system OBJY2 class B (130 °C) or class F (155 °C) is possible. The core insulation in toroidal chokes consists of an elastic epoxy paint, which is suitable for direct wire contact under UL 508c. The toroidal insulation is tested to withstand voltages up to 1.5 kV.