Analog Inputs; Current And Voltage; Thermocouple; Resistance Thermometer (Rtd) - ABB SM3000 User Manual

SM3000
Multipoint Videographic Recorder

7.4 Analog Inputs

7.4.1 Current and Voltage

Warning.

When input 'Type' is set to 'Volts' (see Section 6.6.2,
page 89), input signals with voltages greater than 2 V
(standard inputs) or 1 V (high specification inputs)
must be connected through an external voltage
divider (part no. GR2000/0375).

Input signals with voltages up to 2 V (2000 mV –
standard inputs) or 1 V (1000 mV – high specification
inputs) may be measured without the need for the
voltage divider by setting 'Type' to 'millivolts' – see
Section 6.6.2, page 89.
An external 10  shunt resistor is required for current

ranges.

To avoid damage to multi-channel instruments, high
common mode voltages up to 500 V r.m.s. max. must
be present on all channels, or not at all.

For the standard
channel-to-channel
channels) must not exceed 35 V or permanent
damage to the instrument's input circuitry may occur.
For applications requiring higher levels of isolation
refer to the high specification card.

7.4.2 Thermocouple

Use the correct compensating cable between the thermocouple
and the terminals – see Table 7.1 on page 115.
Automatic cold junction compensation (ACJC) is incorporated
but an independent cold (reference) junction may be used.

7.4.3 Resistance Thermometer (RTD)

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.

7.4.4 Transmitter Power Supply

Note. The power supply board provides a 24 V supply
capable of driving two 2-wire transmitters. Two additional
24 V power supplies are provided on the transmitter power
supply module boards, each of which is capable of driving
two 2-wire transmitters.
114
input card the maximum
voltage (between any two
+
–
10W Resistor supplied
Voltage divider
in accessory pack.
(GR2000/0375)
required for
voltage inputs –
see Warnings
A – Voltage B – Current
White
+
Red
–
Red
3rd Lead
Each lead must be of equal
resistance and less than 10W
D – 3-lead RTD
F – Volt Free Digital Input
Fig. 7.6 Analog Input Connections
Warning. Under no circumstances must the spare input
terminal be linked to the negative.
Note. Refer also to Fig. 7.5 for terminal numbers.
Analog Input
–
+
Tx
–
10W Shunt
Fig. 7.7 Transmitter Power Supply
7 Installation
+
+
–
–
C – Thermocouple
White
+
Red
–
3rd Lead
Sleeved
Link
E – 2-lead RTD
(and resistance)
Logic state Logic state
inactive active
2-wire Transmitter Power Supply
(24V DC, 45mA max.)
+
+
–
IM/SM3000–EN Rev. L