Overview
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 strongly 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. 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 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.
| Schwarzbeck HHS 5210-100-2.5 Specifications | |
| Number of turns (per coil) | 100 |
| Maximum coil current | 20 A, 5 min. |
| Nominal coil current | 12 A continuous |
| Inner side length of the coils | 1.0 m |
| Electrical side length of the coil | 1.04 m |
| Mechanical Dimensions | 1.15 m x 1.20 m x 0.75 m |
| Maximum Coil Separation | 0.70 m |
| Usable Frequency Range | 0 – 10 kHz |
| Inductance (per Coil) | 31.3 mH |
| Resistance (per Coil) | 1.5 ? |
| Resonant Frequency (Pair of Coils) | > 25 kHz |
| Weight | 56 kg |
| The following data is valid for 0.4 m coil distance | |
| Coil Separation acc. IEC 1000-4- 8 | 0.4 m |
| Maximum Magnetic Field Strength | 2900 A/m, 5 min. |
| Nominal Magnetic Field Strength | 1746 A/m continuous |
| Magnetic Fieldstrength, 1 A Coil Current | 145.54 A/m (Coil Dist. 0.4 m) |
| Current required for 1 A/m | 6.87 mA (Coil Dist. 0.4 m) |
| The following data is valid for 0.566 m coil distance | |
| Coil Separation for best uniformity along an axes through the coil centers | 0.566 m |
| Magnetic Fieldstrength, 1 A Coil Current | 124.66 A/m (Coil Dist. 0.566 m) |
| Current required for 1 A/m | 8.02 mA (Coil Dist. 0.566 m) |
| Inductance (Coil pair) | 68.5 mH (Coil Dist. 0.566 m) |
