65
MD7
：
IEC60950
、
IEC61010-1 Fig A.2 External MD(Option)
(2Kohm) for RUN Test MD Circuit
External Measuring Device
The 7630 has an access panel on the back of the instrument that can be removed to access the
MD external PCB. The MD external PCB may be configured for a simple resistive
measuring device or a two-pole measuring device similar to MD 7. The PCB comes
configured with a 1k
Ω
measuring device.
Frequency Check
The Touch Current test can be configured to verify the bandwidth of the leakage current
“voltmeter” by setting the Probe configuration, Probe-HI to Probe-LO, and selecting the
medical device “Frequency Check”. The selection is intended for meter verification
purposes only and has no application for normal testing. The calculation of the displayed
leakage current will use 1000
Ω
for R in the calculation of V/R=I where I is the leakage
current displayed and V is voltage across the measuring device (MD). When an external
frequency generator is applied to the probe inputs, the current display will be equal to Voltage
generator/1000. The readings can then be correlated to verify the voltmeter bandwidth.
Since the voltage is being applied directly across the MD voltmeter amplifier inputs, it is not
necessary to actually install a 1K
Ω
resistor to the external MD input. It is necessary to have
the 0
Ω
resistors installed in position R1 and R3 on the external measuring device PCB to
operate in this mode. If the external measuring device has been populated in a different
configuration, it will be necessary to create a temporary short on R1 and R3 to operate in this
mode. Another option would be to acquire a spare external measuring device PCB for the
meter verification purpose.
A
B
A
B
A
B
A B
A
B
R&C