HA243821
Issue 5 Mar 98
Section 2
Page 2 - 7
MODEL 346 INSTALLATION AND OPERATION MANUAL
2.3.2 SIGNAL WIRING (Cont.)
ATTENUATED DC VOLTAGE INPUTS ABOVE 5 VOLTS
Inputs between 5 V and 100 V dc can be connected
only if a 1 Megohm, 100:1 input attenuator is fitted as
shown in figure 2.3.2b, below. This results in recorder
input voltages of 50 mV with a 5 V signal and of 1 V
with a 100 V signal.
Example
A linear voltage which can vary between 2 to 10 volts is
to be applied to a recorder channel input. Because any-
thing over 5 Volts exceeds the maximumm input volt-
age, an attenuator is used. A standard 100:1 attenuator
will reduce the voltage range to 20mV to 100mV.
RTD (RESISTANCE TEMPERATURE DETECTOR) INPUTS
The recorder supplies the actuation current and connections for 100
Ω
Platinum RTDs (Pt100s). Signal wire size
and length must be chosen to ensure that lead lengths are equal and individual leads do not exceed 10
Ω
each
between the recorder and the RTD.
Figure 2.3.2c Input connections for Resistance Thermometers
CONTACT INPUT (EVENT) CONNECTIONS
These optional inputs (figure 2.3.) permit many recorder functions to be controlled by an external contact closure.
Connections are made (via switches) between the ‘COM’ terminal and the relevant input terminals 1 to 6. Good
quality, low resistance ‘dry’ (not powered) contacts should be used.
See Section 3.4 (Internal triggers and action equations) for a description of the use of Contact inputs.
+
–
Voltages above 5 Volts
Figure 2.3.2b
Input connections for dc voltages above 5 Volts
2-wire RTD
3-wire RTD
4-wire RTD
N.C.
+
–
+
–
+
–
