Dwyer EPTA User Manual

(EPTA-B shown)

Bulletin L-39

EPTA

Analog Current or Voltage to Modulated Pressure Output

and Fail Safe

INSTALLATION

READ THESE INSTRUCTIONS BEFORE YOU BEGIN INSTALLATION.

Ground yourself before touching board. Some components are static sensitive.

MOUNTING:

Circuit board may be mounted in any position. If circuit board slides out of snap track, a nonconductive “stop”
may be required. Use only fingers to remove board from snap track. Slide out of snap track or push against
side of snap track and lift that side of the circuit board to remove. Do not flex board or use tools.

POWER CONNECTIONS - THIS PRODUCT ACCEPTS 24 VDC or 24 VAC POWER.

Be sure to follow all local and electrical codes. Refer to wiring diagram for connection information. Be sure
to make all connections with power off.

1) DC Power - Refer to wiring diagram for connection information.

If the 24 VDC power is shared with devices that have coils such as relays, solenoids, or other inductors, each coil
must have an MOV, DC Transorb, or diode placed across the coil or inductor. The cathode, or banded side of the
DC Transorb or diode, connects to the positive side of the power supply.

2) AC Power - Refer to wiring diagram for connection information.

Check the wiring configuration of any other loads that may be connected to this transformer. If required by
BAS or controller specification, the 24 VAC neutral can be earth grounded at the transformer. Analog input,
digital input, and analog output circuits should not be earth grounded at two points. Any field device connected
to this transformer must use the same common. If you are not sure of other field device configuration, use
separate transformers for isolation.

If the 24 VAC power is shared with devices that have coils such as relays, solenoids, or other inductors, each
coil must have an MOV, AC Transorb, or other spike snubbing device across each of the shared coils. Without
these snubbers, coils produce very large voltage spikes when de-energizing that can cause malfunction or
destruction of electronic circuits. Refer to wiring diagram for connection information.

3) You should measure the actual voltage output of the secondary. If the output is not fully loaded you may read a higher
voltage than the circuit board can handle.

ADJUSTMENT OF GAUGES. If installation requires adjustment of the gauge for proper reading of the face, turn the gauge
no more than 1/2 turn in either direction. O rings in the bottom of the gauge port will allow this without leakage.

Warranty does not include malfunction due to clogged valve. Main air port is filtered with the supplied 80-100 micron
integral-in-barb filter (Part # A-403). Periodically check the filter for contamination and flow reduction. Replace
if needed (Part # A-403) .

The surface between the manifold and pressure transducer is a pressure seal. Minimize stress between the circuit board
and the manifold by holding the manifold in one hand while installing pneumatic tubing onto the fittings, and use care when
removing tubing to avoid damaging fittings or moving manifold.

Dwyer Instruments, Inc.
Michigan City, Indiana

www.dwyer-inst.com

1

EPTA Installation Instructions

P/D 080107

CHECKOUT

For optimum performance and reduced noise, the EPTA-B1 unit requires a branch air line capacity equal to at least
25 feet of 1/4"O.D. polyethylene tubing to operate without oscillation, and the EPTA-S unit requires a branch air
line capacity equal to at least 15 feet of 1/4" O.D. polyethylene tubing to operate without oscillation. Do not power

without main air provided.

With power off, select one of the four input signal combinations by moving the jumper shunt J1
identified as "Input Signal Range Selector". Select a preset pressure output range by moving
jumper shunt J2 identified as "Pressure Output Range Selector", or set custom range as described
below.

SETTING CUSTOM OUTPUT PRESSURE RANGE. Verify the MANUAL/AUTO switch is in the
AUTO position. In AUTO, the manual override pot is inactive, the override contacts are open, and
the analog input signal is supplying the set-point. The offset pot may be adjusted to any desired
offset between 0 and 14 psig. When in the MANUAL position, the override contacts are closed,
the offset pot is inactive and the manual override pot is supplying the set point (the analog input
signal is locked out). Supply power and the LED power indicator will light, but only measurement
will verify proper voltage

1. Setting the minimum pressure. Make sure the signal connections are made and input is at
minimum. Place the manual override switch to the AUTO position. Adjust the OFFSET pot to
the desired pressure output, or until the actuator just starts to move. The adjustment range of
the OFFSET pot is 0 to 9 psig (62.05 kPa), 0 to14 psig (96.53 kPa), or 0 to19 psig (131kPa)
depending on range selected. Zero pot is factory set - do not adjust.

2. Setting the maximum pressure. Now place the manual override switch to the MANUAL
position. Turn the MANUAL pot to produce the maximum branch line pressure available. Turn
the SPAN pot for the maximum desired output pressure, or until the actuator just stops. Be sure

the MAIN air pressure is at least 2 psig greater than the desired maximum branch output
pressure.

3. Repeat. Because the OFFSET and SPAN pots are slightly interactive, steps 1 and 2 must be

repeated until the desired minimum and maximum pressures are repeatable. Since the
MANUAL pot is set for maximum pressure, it is only required that you switch the manual override
switch back and forth from MANUAL to AUTO when repeating steps 1 and 2. Calibration is
usually accomplished in less than 3 iterations. Apply minimum and maximum input signals and
measure response. Response between the minimum and maximum values will be linear,
therefore software algorithms are easy to derive.

The feedback signal range on all selections is 0-5 VDC and is proportional to the output pressure
range selected. The output and feedback signal will continue to vary proportionally if the input signal
is increased beyond its upper limit (if enough main air pressure is available).

Note: If power to the EPTA-S0 or EPTA-B0 is lost, the branch line control valve will close and branch

line pressure will be maintained (assuming no branch line leaks).
If power to the EPTA-S1 or EPTA-B1 (Fail-Safe) is lost, the branch line 3-way valve will exhaust

branch line pressure to 0 psig (0 kPa).

For DIN rail mounting of EPTA-S, use (or order) A-400 Kit.

EU Commission Directive 2002/95/EC (RoHS) Compliant

Power Supply Voltage:

24 VDC (+10%/-5%)
24 VAC (+/-10%) 50/60 Hz at terminals

Supply Current:

180 mA max. (200 mA max., EPTA-B1 model)

Feedback Signal Output:

Factory Calibrated 0 -5 VDC = range selected

Input Signal Ranges:

0-5 VDC@ Infinite ohms
0-10 VDC@ Infinite ohms
0-10 VDC@ Infinite ohms
0-20 mA @ 250 ohms

EPTA Installation Instructions
P/D 080107

Air Supply:

Maximum 25 psig (172.38 kPa), minimum 18 psig (124.11 kPa)
main air supply, 0-10 psig ( 68.95 kPa), 0-15 psig (103.43), and 0-20
psig (137.9 kPa) jumper selectable output pressure ranges.

Air Flow, @ 20 psig (137.9 kPa) main/15 psig

(103.43 kPa) Out, 750 scim

Exhaust rate: - 750 scim

Accuracy: 1% full scale at room temperature

Override Contact Rating: 24 VAC or 24 VDC, 1A maximum

www.dwyer-inst.com

2% full scale @ 32 to 120OF (0 to 48.8OC)

Dwyer Instruments, Inc.

2

Michigan City, Indiana