Dwyer BAT - Manual (Page 2)

GENERAL INFORMATION, SPEcIFIcATIONS and INSTALLATION
The Dwyer Instruments Inc. Series BAT is a blind (non-
indicating) 4 to 20 mA transmitter, designed for use with Series
EFS2, IEFS, PDWS, TBS and FLMG flow sensors. It accepts a
pulse frequency input from the flow sensor, and converts this
input into a continuous analog output signal. Power for the
transmitter is taken from the current loop itself, so only two
wires are required. The digital design makes it possible to span
the unit in the field without tools. The frequency at which 20
mA is desired is entered on a set of rotary switches, and an
internal microcontroller automatically scales all other values
accordingly. An additional benefit of the microcontroller is its
ability to average inputs, for smoothing of the output signal.
The degree of averaging can be selected in the field, from 2 to
16 seconds.
For maximum environmental protection, the electronic
components are encased in a special semi-flexible urethane
potting material. The housing is cast from aluminum and
fuse-coated. The clamshell housing offered in the BAT-M is
connected directly to the flow sensor or, in the wall mount
version, BAT-W, provided with mounting feet.
The BAT will operate on a relatively wide range of current loop
voltages, 24 to 36 Vdc. Lower voltages limit the load that can
be applied to the loop without distortion of the signal. (See
Load/Supply chart if there is a question regarding voltage vs.
load.) A built-in power regulator supplies the appropriate power
to the flow sensor.
Typical applications for this transmitter are telemetry (or
SCADA), distributed control systems, programmable controllers,
SETTINGS, cALIBRATION and FREQuENcY
Mounting. The BAT-M can be mounted on the flow sensor.
The BAT-W wall mount comes with mounting feet and
requires four screws to attach it to any stable surface.
connection. On either style of housing, the upper portion
must be removed to make connections. Use a standard hex
wrench (5/32” or 4 mm) to loosen the screws, then remove
the upper half. The connections are made to terminal blocks
in the upper half, which contains the potted electronics.
Consult the Connections diagram before connecting to the
current loop. The only connections required on a BAT-M are
the positive and negative loop connections. On a BAT-W,
the sensor must also be connected, since it is remote from
the transmitter. Be careful to follow the color coding of the
flow sensor wires in order to establish the correct polarity.
Incorrect polarity can damage the sensor.
Refer to "Terms and Conditions of Sale" in our catalog or on
our website. Contact customer service to receive a Returns
Goods Authorization number before shipping your product
back for repair. Be sure to include a brief description of the
problem plus any relevant applciation notes.
GENERAL INFORMATION INSTALLATION SETTINGS
Setting Frequency. The BAT converts a train of off/on pulses
from the flow sensor into a continuous mA signal that ranges
from 4 mA at zero flow to 20 mA at the desired maximum flow.
The desired maximum is determined by the user and entered
as a frequency as follows:
1)
2)
3)
4)
Setting Averaging Time. For most applications this step can
be ignored, as the standard setting will work fine. However,
when a particularly steady output signal is desired, or in a
large pipe, a larger averaging period may be desirable. Note
however that the averaging period requires a tradeoff, since
a longer averaging period implies a slower response time. If
steady signal is more important than fast response, increase
the averaging time as desired. See the diagram below for the
switch positions and their corresponding times.
Decide what flow rate should represent the top of the
scale. This is ordinarily the maximum expected flow, or
a value just above it, in gallons per minute.
Locate the K-factor of the flow sensor (found on the
meter or fitting, or in the instruction manual, depending
on meter model). The K-factor is the number of pulses
the flow sensor produces per gallon of flow.
Calculate frequency, using this formula:
K-Factor x Top Flow (GPM) = Frequency
60
Enter the frequency using the four rotary Frequency
switches. Note the decimal point between the third
and fourth switches.
checking calibration
Normally it should not be necessary to check calibration, since
the digital design of this unit virtually eliminates drift. However,
there are two types of calibration check that can be performed.
Look at the diagram below to locate the 4 and 20 mA force
switches. To force the 4 mA output, put its switch in the up
position. Check the current output at the Power terminals, and
if necessary, trim to 4.00 mA using the appropriate trimpot.
Return the switch to the down position, and repeat the process
with the 20 mA switch and appropriate trimpot.
In an installation with an estimated maximum flow rate
of about 150 GPM, a flow rate of 170 GPM is selected
as the full-scale maximum, the flow at which the current
loop will register 20 mA.
In this example, the K-factor (found on the meter or
fitting, or in the manual) is “K = 54.50”.
Calculate the frequency as
1 5 4 . 4
Rounding to one decimal point, enter 154.4 on the
rotary switches by turning the rotary switch pointers
to the desired digits.
= 154.42
54.50 x 170
60
SETTING FREQuENcY ExAMPLE
1)
2)
3)
4)
Switch Position
Seconds L R
2 down down
4 down up
8 up down
16 up up
24 to 36 Vdc
32 to 130˚ F (0 to 55˚ C)
Open-collector solid state sensor
2 to 16 seconds (switch selectable)
2 to 60 seconds; 90% of full-scale
(dependent on input averaging)
10 Hz (@20 mA)
999.9 Hz
4 Rotary DIP switches
Proportional 4 to 20 mA
Power
Temperature
Input
Input Averaging
Response Time
Frequency Minimum
Maximum
Setting
Output
SPEcIFIcATIONS*
*Specifications subject to change
WARRANTY/RETuRN