BEKA Advisor A90-SS, Руководство пользователя

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3. APPLICATIONS
3.1 Power supply
3.1.1 Mains powered version
The mains powered version of the A90-SS panel
mounting meter will operate from a wide range of
voltage and frequency ac supplies.
Voltage 90 to 264V rms ac
Frequency 47 to 63Hz
Power 2.5W
The supply should be well regulated and free from
transients.
3.1.2 DC powered version
The DC powered version of the A90-SS panel
mounting meter is designed to be operated from a
nominal 24V dc instrument power supply but, as
shown below, will function with a wide range
supply voltages.
Voltage 10 to 36V dc
Current 200mA at 10V
56mA at 36V
3.2 Signal inputs
The A90-SS panel meter can measure current and
voltage process signals and display them in
meaningful engineering units. The meter can also
display temperature in a variety of formats from a
Pt100 resistance thermometer primary element.
Selection of the input type is made within the
configuration menu which is described in section 5
of this manual. Input terminals also vary for
different inputs as shown in Fig 6.
3.2.1 Current input
The A90-SS panel meter can measure and display
in engineering units any process signal
represented by an analogue linear or square law
current such as a 4/20mA process signal. The
A90-SS has two current input ranges 4-20mA and
0-50mA dc.
The current input terminals 13 and 14 are
galvanically isolated from the A90-SS meter power
supply and all other outputs which allows the A90-
SS meter to measure the current in any process
loop without affecting the accuracy of the loop.
When connected in series with a current loop the
A90-SS panel meter introduces the following
voltage drops:
At 20mA 1.0V
At 50mA 1.5V
Fig 2 shows how the A90-SS panel meter should
be connected to measure a process current.
Fig 2 A90-SS Process panel meter measuring
current.
3.2.2 Voltage input
The A90-SS panel meter can measure and display
in engineering units any linear process signal
represented by an analogue voltage such as a 0 to
1V signal. The voltage input terminals 11, 12 and
13 are galvanically isolated from the A90-SS meter
power supply and all other outputs. There are
three dc voltage input ranges:
Input
Terminals resistance
0 to 0.1V 13 (0V) and 12 (+ve) 5M Ω
0 to 1.0V 13 (0V) and 12 (+ve) 5M Ω
0 to 10V 13 (0V) and 11 (+ve) 1M Ω
The input resistance of all the voltage inputs is high
allowing the A90-SS meter to measure any
process voltage signal without loading it and
changing the value. Fig 3 shows how the A90-SS
panel meter should be connected to measure a
process voltage.
Fig 3 A90-SS Process panel meter measuring
voltage.
3.2.3 Resistance thermometer input
The A90-SS panel meter can measure the
resistance of a single Pt100 BS EN 60751 platinum
resistance thermometer and display the
corresponding temperature in a variety of units
including ºC and ºF. The resistance thermometer
may be connected to the meter via two or three
wires. The differential output of two resistance
thermometers can also be measured and
displayed.
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