Ashcroft A2 - Heavy industrial pressure transmitter - Manual (Page 2)

A2 PRESSURE TRANSMITTER
INSTRUCTION SHEET
Mounting
The A2 transmitter requires no special
mounting hardware, and can be mounted
in any plane with negligible position error.
Although the unit can withstand normal
vibration without damage or significant
output effects, it is always good practice
to mount the transducer where there is
minimum vibration.
For units with NPT type pressure fittings
apply Teflon ® tape or an equivalent
sealant to the threads before installing.
When tightening, apply a wrench to the
hex wrench flats located just above the
pressure fitting.
DO NOT tighten by using
a pipe wrench on the housing.
Noise
For minimum noise susceptibility, avoid
running the transducer’s cable in a con-
duit that contains high current AC power
cables. Where possible avoid running
the cable near inductive equipment.
Shielded Cable
Units with shielded cable electrical termi-
nation, connect the drain wire to the
guard terminal on the read out device or
measuring instrument, if available. In all
other cases connect to the ground or to
the power supply negative terminal.
Sintered Metal Filter
All units less than 500 psi include a small
metal sintered filter at the top of the unit.
This is necessary to equalize the internal
pressure with atmospheric pressure but
can be a point of moisture ingress.
Power Supply
Power Supply Voltage
Output Signal Min Max
0-5Vdc 10V 30V
1-5Vdc 10V 30V
1-6Vdc 10V 30V
0-10V 14V 30V
4-20mA 12V* 36V
* For transmitters with 4-20mA output
signal, the minimum voltage at the termi-
nals is 12Vdc. However, the minimum
supply voltage should be calculated
using the following graph and formula.
Vmin = 12V+ (.022A x RL) (includes a 10% safety factor)
RL = RS + RW
RL = Loop Resistance (ohms)
RS = Sense Resistance (ohms)
RW = Wire Resistance (ohms)
10
1000
800
600
400
200
0
20 30
Operating
Region
Loop Supply Voltage (Vdc)
Loop Supply Voltage vs. Loop Resistance
L
o
o
p
R
e
s
is
ta
n
c
e
(
O
h
m
s
)
+
+ –
POWER
SUPPLY
(+)
(–)
TRANSDUCER
–
V+
V–
PIN 1
PIN 2
4-20mA
METER
OR OTHER DEVICE
+
+
–
–
POWER
SUPPLY
METER
OR OTHER DEVICE
TRANSDUCER
(Common)
(+ Power)
(+ Output)
PIN 1
PIN 2
PIN 3
3-Wire Voltage
A2 Wiring Diagrams
Zero and Span Adjustment
Instructions below apply to the particular
configurations noted, not all A2 configura-
tions offer Zero and Span access. While
Zero adjustment is not normally neces-
sary, it may be desirable to trim out any
offset in the system. However, proper
Span calibration requires a pressure stan-
dard three to five times more accurate
than the accuracy of the transducer, and
there may also be interaction of Span on
Zero.
1. Side access zero and span adjust-
ment (Enclosure Options “Z,” “Y”) A2
configurations with side access “Z” and
“S” potentiometers (pots) have a black
plastic access sleeve towards the elec-
A2 transducer has internal transient
protection: for safety, limit line-to-
ground voltage to 36 Vdc max.
© 2011 Ashcroft Inc. All rights reserved. 250 East Main Street, Stratford, CT 06614 USA Tel: 203-378-8281, Fax: 203-385-0402 www.ashcroft.com
All sales subject to standard terms and conditions of sale. I&M011-10102-A2. Rev. 02/14
trical termination end of the unit (see
diagram on front page).
To gain access to the zero and span
adjustment pots, slide the access
sleeve upward toward the connector.
On the label there is a “Z” and “S” to
indicate zero and span. (Looking at the
A2 vertically as in the diagram, zero is
on the left and the span is on the right).
Using a small trim pot adjustment tool
you can adjust zero ±10% of full scale
and span ±10% of full scale.
2. Top/rear access zero and span
adjustment
Access to “Z” and “S” pots via the top
(electrical termination end) of the unit is
standard on all “S” enclosure units with
4-20mA output. Access is gained by
removing the black threaded cap, once
removed you will see the pots indicated
by “Z” and “S”
respectively as
shown below. Using
a small trim pot tool,
you can adjust zero
±10% of full scale
and span ±10% of
full scale.
Recalibration Instructions:
1. Apply 0% full scale pressure.
2. Adjust the output using the zero adjust
trim pot.
3. Apply 100% full scale pressure.
4. Adjust the output using the span adjust-
ment trim pot.
5. Repeat steps 1 through 4 as necessary.
.0
6 2
Z S
Z S
“Z” and “S” pots