5560K Precision Inductive Voltage Divider
The 8 Dial Inductive Voltage Divider Type 5560K uses the two stage system and is based on 
work carried out at the National Physical Laboratory. 

High quality mumetal cores are used for the
toroidal windings and the whole assembly is
magnetically shielded. 
The ratio range is from 1 to -10^-5 through 
zero in steps 10^-8. 
The first four dials are calibrated 0 to 9 and 
the last four -1 to 10 through zero, providing an 
overlapping of dials on the low end. 
The frequency range is from 30 to 1000 Hz. 

The accuracy of the device is within 5 parts in 10⁸ of the output. The maximum input voltage is 20% of the frequency, the frequency being expressed in Hz, for example: at 1000Hz the maximum input voltage is 200Volts and at 30Hz it is 6Volts. The input impedance is approximately 1MΩ, the out impedance approximately 2.5 Ohms. Terminals are provided for the magnetic winding, the measuring winding output and earthed screen which is a mumetal box enclosing the cores. 

The instrument is mounted in a teak case and fitted with a gray metal top panel with clear engraving and index windows for each dial.

Specifications

Notes

The measuring winding has a very high input impedance when the energizing winding is supplied with a voltage equal to that applied to the measuring winding.

For highest accuracy the measuring winding should be connected to the precise point in the circuit which defines the required ratio, thus avoiding errors due to voltage drop in the connecting leads.

The shield terminal is driven by the magnetizing winding to a potential equal to the ratio shown on the first dial plus 0.05. i.e. When the first dial reads 0.3 the shield is held at the potential corresponding to 0.35. This may be used to drive a fully screened circuit and will not load the measuring

In any circuit measuring to very high resolution it will be necessary to null the inevitable quadrature component to obtain high accuracy. Whatever method is used it is essential to ensure that there is no phase defect which may cause appreciable error.

If two pure resistors are being compared, a differential air capacitor will provide quadrature compensation but in more complex circuits it may be necessary to inject the quadrature compensation into the detector via a suitable transformer.

The terminal marked CASE should be taken to ground to avoid disturbance due to hand capacitance.