Keithley 3700 Series User Manual

Section 8: Theory of operation Series 3700A System Switch/Multimeter Reference Manual
8-18 3700AS-901-01 Rev. D/June 2018
VMEAS open voltage (dry-circuit)
If either Input Sense HI or Sense LO V
MEAS
is outside the enclosed table voltages, the A/D stops in
less than 100 s and returns an overflow reading.
Range
V
MEAS
SHI or SLO high limit open
lead detection
V
MEAS
SHI or SLO low limit open lead
detection
1 Ω
> 27 mV
< –10 mV
10 Ωto 2 kΩ
> 20 mV
< –10 mV
Calculated measurement open voltage (dry-circuit)
A calculated measurement that exceeds 120 percent of the range will return an overflow reading.
INPUT Sense HI is internally connected to INPUT HI. The connection allows proper open circuit
voltage, even with Sense HI disconnected. With INPUT Sense HI disconnected, and the other inputs
properly connected, the measurement will read the V
DUT
and R
LEADVOLTAGE
drop.
For dmm.drycircuit = dmm.ON and dmm.opendetector = dmm.ON, I
OPENLEAD
will be disabled,
but a print(dmm.opendetector) will still return 1.0.
Open thermocouple detection
The Series 3700A open thermocouple detection works in similar fashion to the open lead detection.
Refer to Open lead detection (on page 8-13). The open thermocouple detection performs as follows:
• V
MEAS
open voltage: If Input HI V
MEAS
is outside 120 mV, the A/D will stop in less than 100 µs
and return an overflow reading.
• A calculated measurement outside of the ranges in the following table will cause the "Overflow"
message to be displayed.
Type
Range
J
–200 °C to +760 °C
K
–200 °C to +1372 °C
N
–200 °C to +1300 °C
T
–200 °C to +400 °C
E
–150 °C to +1000 °C
R
0 °C to +1768 °C
S
0 °C to +1786 °C
B
+350 °C to +1820 °C
• If during a measurement cycle, with dmm.opendetector = dmm.ON, the ohm's function 100 µA
I
SOUR
is pulsed on and off before the start of each measurement. The A/D will monitor V
MEAS
for
0.8 ms. During the IONPHASE, if a resistance of more than 1.15 kΩ is detected, or the input
voltage is greater than 120 mV, the A/D will stop in less than 100 µs and return an overflow
reading. If less than 1.15 kΩ is detected and the input voltage is in the range of ±120 mV, the
open lead detection current is turned off and a normal thermocouple temperature measurement is
performed (see Thermocouple connections (on page 4-25)).

Keithley 3700 Series Specifications

General

Brand	Keithley
Model	3700 Series
Category	Multimeter
Language	English