Keithley 3730 User Manual

Series 3700
System Switch/Multimeter User's Manual Section 5:
Basic Digital Multimeter (DMM) Operation
Document Number: 3700S
-900-01 Rev. A / August 2007 5-
35
NOTE 1. INPUT Sense HI is internally connector 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.
2. For dmm.drycircuit = dmm.ON and dmm.opendetector = dmm.ON, IOPENLEAD will
be disabled, but a print(dmm.opendetector) will still return 1.0.
Temperature measurements
The Series 3700 can measure temperature using various thermoelectric transducers including:
thermocouples, thermistors, and 3 or 4-wire resistance temperature detectors (RTDs). When
deciding which type to use, keep in mind that the thermocouple is the most versatile and useful
for significant distances between the sensor and the instrument, the thermistor is the most
sensitive, the 4-wire RTD is the most stable, and the 3-wire RTD minimizes the number of
conductors per sensor (3).
Thermocouples
For thermocouples, temperature measurement range depends on which type of thermocouple is
being used. Thermocouples that are supported include types J, K, N, T, E, R, S, and B.
Type
Range
Resolution
J
-200°C to +760°C
0.001°C
K
-200°C to +1372°C
0.001°C
N
-200°C to +1300°C
0.001°C
T
-200°C to +400°C
0.001°C
E
-150°C to +1000°C
0.001°C
R
0°C to +1768°C
0.1°C
S
0°C to +1786°C
0.1°C
B
+350°C to +1820°C
0.1°C
When two wires made up of dissimilar metals are joined together, a voltage is generated. The
generated voltage is a function of temperature. As temperature changes, the voltage changes.
The thermocouple voltage equates to a temperature reading. This is the basic operation
principle of the thermocouple.
When you connect a thermocouple directly to the input of the Series 3700, at least one of those
connections will be a junction made up of two dissimilar metals. Hence, another voltage is
introduced and is algebraically added to the thermocouple voltage. The result will be an
erroneous temperature measurement.
To cancel the affects of the unwanted thermal voltage, the thermocouple circuit requires a
reference junction that is at a known temperature.

Keithley 3730 Specifications

General

Brand	Keithley
Model	3730
Category	Multimeter
Language	English