Helmholtz-Coils are especially designed to generate precisely defined magnetic fields from DC to the upper end of the audio frequency range and beyond. The generated fields are in a strong linear relation to the coil current. The field strength can be calculated exactly by analytical (or numerical) methods, based on the coils' geometry, the number of turns, and the coil current. Therefore the HHS 5206-8 is ideally suited for the calibration of magnetic field probes or sensors. Due to the high temperature proof Teflon-coated wire packet, it is possible to generate magnetic fields up to approx. 1000 A/m (for a short time). Typical applications are magnetic immunity testing according to automotive standards or MIL-461F. When generating magnetic fields with Helmholtz coils the coil current is directly proportional to the magnetic field strength.

The calibration of the magnetic field is finally traceable to a current measurement (or to a voltage drop at a known resistor). The Helmholtz Coil itself is usually considered as a primary standard due to the easily calculable relation between current and field strength. If this relation should be controlled, a loop sensor or monitoring loop can be used to determine the actual field strength.

The Helmholtz-Coils should be installed on a desk in a sufficiently large separation from sources of unintentional magnetic fields, e.g. transformers in power supplies, conductors carrying high currents, computer monitors, loudspeakers, cathode ray tubes (CRT), and more.... All kinds of magnetic material (e.g. steel, Nickel, Cobalt) should be removed from the near surrounding of the coil. The wires which are used to connect the current source with the Helmholtz- Coil should be twisted to avoid an unwanted injection of magnetic flux. The coil terminals are assigned with the characters A, B, C, and D. The generator (current source, audio-amplifier...) is connected to terminals A and C, the terminals B and D are connected with the short cable supplied with the coil.

Specifications:       

  Recommended accessories:

NFCN 9732 85 kHz - Compensation Network

 The compensation network NFCN 9732 85 kHz consists of a high current/ high voltage variable capacitor.

The compensation capacitor reduces the total impedance of the series circuitry consisting of the Helmholtz coil HHS 5206-8 and the NFCN 9732 85 kHz at the operating frequency band of 80-90 kHz. It allows continuous currents of up to 15 A_rms at generator voltages of less than 40 V_rms.

Application: Immunity test inductive changing 85 kHz