The local amplifier serves three functions:

a. It provides a characteristic impedance termination for the signal cable from the remote amplifier,

b. It provides additional gain for driving the squaring circuit, and

c. It contains the attenuation networks necessary to divide the six decades of flux coverage into twelve ranges. Its gain is nominally 50, but it is adjustable over a ±30 percent range from its nominal value.

7. 1. 3 Inverter

The inverter is a unity gain amplifier whose function is to receive the signal from the local amplifier and provide two outputs to the mean square analog, one output 180 degrees out of phase with the other.

7.1. 4 Mean Square Analog

The mean square analog is a piece-wise linear circuit whose output current varies as the square of the input voltage. By passing the current through a 10, 000-ohm resistor, a voltage is obtained that is fed to a unity gain d-c amplifier which provides the readout signal and operates the trips. A capacitor in parallel with the IQ, 000-ohm resistor controls the averaging time constant of the system. .