The primary function of the compensation network NFCN 9731-100 is to provide a serial compensation of the inductance of i.e. the HHS 5230-100 at operation frequencies of 16.666 Hz, 50 Hz, 60 Hz, 150 Hz, and 180 Hz. These operation frequencies are stipulated by SAE J551-17 (Vehicle Electromagnetic Immunity – Power Line Magnetic Fields)

The NFCN 9731-100 provides two separate channels utilizing a shared control unit. Thus every single coil of the Helmholtz coil is powered by a separate amplifier. The current flowing through the coils can be checked using the built-in RMS-ampere-meters. The compensation capacitor reduces the overall impedance of the series circuit consisting of the Helmholtz coil HHS 5230 and the compensation network NFCN 9731-100 at the applied operating frequency and allows currents up to 8 Arms at a generator voltage of less than 60 Vrms.  To protect the amplifier and the compensation network NFCN 9731-100 is equipped with a 10 A fuse. An overvoltage protective circuit connects a damping resistor in parallel to the capacitor when exceeding the maximum operating voltage (at currents higher than 8 Arms) 

The Helmholtz coil has to be connected (eventually using a load resistance in series) to the terminals “OUTPUT” and “COMMON”. The generator (output of the amplifier) has to be connected to the terminals “INPUT” and “COMMON”. The terminal “COMMON” may be grounded. The wiring must not be done in a different order. Otherwise, the protection circuit does not work! 

The signal level has to be increased slowly until the maximum current has been reached. Abrupt overload leads to voltage spikes. The protection circuit is too slow to prevent damage in case of abrupt overload. The NFCN 9731 has to be controlled manually.

 Specifications: