Figure 2. VTM dc current (high)

TB 9-4910-556-35

(5) Wait for offset values to appear on display. Offset values will be between -225

and +225.

(6) Place shorting plugs in 100 A position on dc current shunt.

(7) Adjust dc power supply No. 2 for 15 mV (15 A output) on digital multimeter.

(8) Press and release TEST pushbutton. If a - (negative) output occurs, reverse the

current probe. VTM should display between 13.55 and 16.45. Record indication.

(9) Adjust dc power supply No. 2 for 100 mV (100 A output) indication on digital

multimeter.

(10) Press and release TEST pushbutton. VTM should display between 91.95 and

108.05. Record indication.

CAUTION

While performing this paragraph, minimize the time that

current is running through the loop. High current will cause

the wire to heat, thus increasing resistance and decreasing the

loop current.

(11) Connect equipment as shown in figure 2.

NOTE

Fabricate a current stimulus loop as shown in figure 2. The

loop design should be 20 turns of No. 10 insulated copper wire

with a bundle diameter of the turns being no more than 1 inch.

The inside diameter of the loop should be 6 inches ±1 inch.

Care should be taken to ensure that the loop does not overheat.

Figure 2. VTM dc current (high) - equipment setup.

NOTE

Clamp current probe to stimulus loop with arrow on probe

pointing in direction of current flow.