9
4.3
Input Lead Connections
Always make the connections to the Model 390-2 in accordance with the direc-
tions given in the following paragraphs before making connections to the power
source.
When testing line-operated devices, always use the Break-In Cable Assembly
supplied with the Instrument (see Figure 4-1 on page 7). Make up a cable adapter
set for use on 240 VAC line-operated devices (see Figure 4-3 on page 12).
If unable to use the Break-In Cable Assembly, use the special test lead set. For
line voltages up to 150 volts, connect the ±V and the 150V jacks across the line
and the ±A and the 3A or 15A jacks in series with the load for 300 and 1500 watt
ranges respectively. The leads are color coded to match the colored dots of the
respective jacks (see Figure 4-2). For line voltages between 150 and 300 volts,
connect the ±V and the 300V jacks across the line, and the ±A and the 3A or 15A
jacks in series with the load for the 600 and 3000 watt ranges respectively.
4.4
DC Voltage Measurements 0-150V, 0-300V
The voltmeter may be used to measure DC voltages, but NOT DC current or
power. For measuring DC voltages, follow the same procedure as for AC voltage
measurement, as discussed in the following paragraph 4.5.
4.5
AC Voltage Measurements, 0-150V, 0-300V
1.
Connect the leads from the Break-in Plug Assembly according to color as
shown in Figure 4-1. Connect the white lead to the jack marked 150V when
testing 120 volt devices, or to the jack marked 300 V when testing 240 volt
devices.
2.
Insert the Break-In Plug into the outlet of the AC line to be measured. See
paragraph 4.3 for 240 volt line measurement, or use of special test leads.
3.
Read the voltage on the top arc of the meter scale, using the figures 0-150 for
the 150V range and 0-300 for the 300V range. The first heavy line above
zero represents 25 on the 0-150 range and 50 on the 0-300 range. When the
object under test is plugged into the Break-In Plug, the voltmeter will indicate
if there is a voltage drop in the line. The voltmeter can also be used to
indicate voltage drop between no load and full load operation.
4.6
AC Current Measurements, 0-3A, 0-15A
NOTE: DC current will damage the Instrument transformer.
1.
Connect the leads from the Break-In plug according to color as shown in
Figure 4-1 on page 10. To use the 3A range, connect the red lead to the
terminal marked “3A”. Use the 0-300 scale and drop two zeros (divide by
100).
2.
When the 15A range is to be used, connect the red lead to the terminal
marked “15A” (use the 0-150 scale and divide by 10).
When the appropriate value of current is unknown, always use the higher range
first as a protection to the meter.