BEAMEX MC4 - Resistance and RTD Measurement, Connections; 4-Wire System

Related Information
118 MC4 User Guide
Resistance and RTD Measurement, Connections
The two main problems in resistance and RTD measurement are the
effects of wiring resistances and thermovoltages in the resistance
measurement circuit. If possible, use 4-wire connection to eliminate
the effect of wiring resistance. The special resistance measurement
sequence of MC4 eliminates the thermovoltages of the resistance
measurement circuit.
MC4 continuously checks the connection type during resistance and
RTD measurement. The found connection type is displayed on the
resistance or RTD measurement window.
4-wire System
When 4-wire system is used, MC4
displays the symbol shown on the
left.
MC4 sources current through the
resistor from the two left side
terminals. MC4 measures the
voltage drop across the resistor
from the two right side terminals.
The 4-wire method gives the
resistance between the terminals
of the resistor, it is insensitive to
the resistance of the connection
wires.
M e a s u r e
M a x 6 0 V , 3 0 V , 1 0 0 m A
T / C
m V
s e n s e
R , R T D R m e a s
V , I ,
V , I ,
T e m p e r a t u r e / G e n e r a t e
3-wire System
When 3-wire system is used, MC4
displays the symbol shown on the
left.
MC4 sources current through the
resistor from the two left side
terminals. MC4 measures the
voltage drop across the entire
current loop and across the low
side connection wire. If both left
side connection wires are
identical, MC4 can compensate
for the resistance of the
connection wires.
M e a s u r e
M a x 6 0 V , 3 0 V , 1 0 0 m A
T / C
m V
s e n s e
R , R T D R m e a s
V , I ,
V , I ,
T e m p e r a t u r e / G e n e r a t e