Dc v, Hermocouples, Oltage – Sensoray 7429 User Manual
Page 33: Three-wire connection, Four-wire connection
no current passes through the sense lines, therefore no voltage develops across the sense
wires.
Three-wire connection
Using three wires has the advantage of eliminating current through one of the two sense
leads. This yields a 50% reduction in lead-loss errors compared to the two-wire circuit.
Using four wires eliminates all error due to lead-loss.
We recommend use of the four-wire circuit using four-conductor shielded cable. You
should always use shielded cable for RTD's regardless of which circuit you choose for
your application. Make sure you connect the cable shield only to the channel SHIELD
pin.
Four-wire connection
T
HERMOCOUPLES
AND
DC V
OLTAGE
Thermocouple and DC voltage inputs are connected directly to the channel SENSE+
and SENSE- pins. The positive wire is connected to SENSE+, while the negative wire
is connected to SENSE-.
Sense+
Sense-
Power+
Power-
Shield
Sense+
Sense-
Power+
Power-
Shield