c. Resistance. There are four resistance ranges: 0-199.9mOhms,
0-1999mOhms, 0-19.99ohms, and 0-199.9ohms. Accuracy is one percent of full scale.
Resistance is measured by monitoring the voltage across the UUT when the dc current is
passed through it. The four-terminal measurement method is used for the mOhms ranges,
and the two terminal method is used for the ohm ranges. Both mOhms and ohms are
d. Voltage. There are four voltage ranges: 0-199.9mv, 0-1999mv, 0-199.9v, and
0-500v. Readings are root-mean-square (rms) ac+dc or dc only. Accuracy is one percent
of full scale. The AAMI load is used for these tests. Both mv and volts are autoranging.
load is recommended by the Association for the Advancement of Medical Instrumentation (AAMI),
Safe Current Limits Standard (ANSI/AAMI ESI-1985) (revision of ANSI/AAMI SCL-12/78).
The AAMI load aids in determining the actual voltage or unit shocks to the patient. If there is no
load, there is no current. Figure 1-1 shows the load. The result is a frequency response which
is flat to the 1 kiloHertz (kHz), then rolls off at 20 decibel (dB) per decade, and levels off at 1
megaHertz (mHz) attenuated by the 40dB. The measurement circuit adds an additional
roll off at approximately 3dB at 1mHz. Measurement of accuracy is one percent of range
from 40Hz to 1000Hz, 2.5 percent of range from 1kHz to 100kHz, and 5 percent of range
from 100kHz to 1mHz.
f. Test Receptacle. This supplies power to the UUT. It supplies 120vac at 15a
maximum or 6a at 230v (50/60Hz). Front panel toggle switches select power ON/OFF,
NORMAL/REVERSE POLARITY, OPEN/CLOSED GROUND to the equipment under test.
Figure 1-1. AAMI load diagram.