Analog Inputs - ABB SM1000 User Manual

5.4 Analog Inputs

5.4.1 Current and Voltage – Fig. 5.6
Warnings.
• When input 'Type' is set to 'Volts' (see Section
4.6.2), inputs be connected through an
must
external voltage divider (part no. GR2000/
0375)
• Input signals with voltages up to 2V (2000mV) may
be measured without the need for the voltage divider
by setting 'Type' to 'millivolts' – see Section 4.6.2.
• An external 10Ω shunt resistor is required for current
ranges.
• To avoid damage to multi-channel instruments, high
common mode voltages up to 500V r.m.s. max.
must be present on all channels, or not at all.
• The maximum channel-to-channel voltage (between
any two channels) must not exceed 12.5V or
permanent damage to the instrument's input
circuitry may occur. To prevent such damage, link
the negative terminals on all inputs. For applications
where the available isolation is required, this link
must not be fitted.
5.4.2 Thermocouple – Fig. 5.6
Use the correct compensating cable between the thermocouple
and the terminals – see Table 5.1.
Automatic cold junction compensation (ACJC) is incorporated
but an independent cold (reference) junction may be used.
5.4.3 Resistance Thermometer (RTD) – Fig. 5.6
On applications requiring long leads it is preferable to use a
3-lead resistance thermometer.
If 2-lead resistance thermometers are used, each input must be
calibrated to take account of the lead resistance.
5.4.4 Transmitter Power Supply – Fig. 5.7
Note. The power supply board provides a 24V supply
capable of driving two 2-wire transmitters. Two
additional 24V power supplies are provided on the
transmitter power supply module boards, each of
which is capable of driving two 2-wire transmitters.
+
–
10Ω Resistor supplied
Voltage divider
in accessory pack.
(GR2000/0375)
required for
voltage inputs
A – Voltage
B – Current
White
+
Red
–
Red
3rd Lead
Each lead must be of equal
resistance and less than 10Ω
D – 3-lead RTD
F – Volt Free Digital Input
Warning. Under no circumstances must
the spare input terminal be linked to the negative.
Note. Refer also to Fig. 5.5 for terminal numbers.
Fig. 5.6 Analog Input Connections
2-wire Transmitter Power Supply
(24V DC, 45mA max.)
Analog Input
– +
+
Tx
–
10Ω Shunt
Fig 5.7 Transmitter Power Supply
5 INSTALLATION...
+
+
–
–
C – Thermocouple
White
+
–
3rd Lead
Sleeved
Link
E – 2-lead RTD
(and resistance)
Logic state Logic state
inactive active
+
–
83