Marsh Bellofram Type Transducer
Fairchild Type Transducer
Flowserve Type Transducer
EPC Type Transducer550ACT Electro Pneumatic Transducer
The 550ACT is the EAA-550 series built to the most common code: A for a 4-20 mA input, C for a 3-15 psig (0.20-1.0 BAR) output, T for a terminal block. It is the miniature transducer for a standard loop on a standard spring, wired straight into a terminal rather than through a plug or a pigtail.
What This Model Is
Type EAA-550 series I/P and E/P transducers are electronic pressure regulators that convert a variable signal to a proportional pneumatic output. The ACT is the configuration that pairs the standard 4-20 mA loop signal with the standard 3-15 psig output and a terminal block termination, in the miniature body the series is built around.
How It Works
The 550 family converts 4-20 mA into a 20-100 kPa pneumatic signal. Because it is an open-loop conversion instrument with no feedback from the valve stem, the connected valve has to be chosen to suit: the spring compression coefficient must sit in the 20-100 kPa band, or the valve will not travel through its full stroke.
550ACT Electro Pneumatic Transducer On Our Benches
Studio and workshop photographs of the units as built, not renderings.
What You Get From This Model
Wired, not plugged
The terminal block suits a field installation where the cable is glanded into the instrument and landed on screws.
Standard loop, standard spring
4-20 mA to 3-15 psig is the pairing most pneumatic control valves are built around, so no adapter or range change is needed.
Small enough for a crowded valve
The miniature 550 body leaves room on the yoke for the positioner, the limit switch box or the solenoid that shares the bracket.
Upgrade path on the same code
Changing one letter moves the output to 3-27, 6-30 or a zero-based range without changing the instrument family.
Where It Is Used
- Control valves on a standard 20-100 kPa spring
- Field instruments cabled and glanded rather than plugged
- Compact valve assemblies with several accessories on one yoke
- Replacement of a failed miniature E/P regulator
Who Orders It
- Instrument technicians terminating field cable at the instrument
- Valve workshops assembling compact actuator packages
- Plants standardising on one miniature I/P configuration
- Distributors stocking the most-asked-for 550 build
What This Model Fixes
There is no room left on the yoke
The miniature body fits where a full-size transducer will not.
A plug-in termination is wrong for the installation
The terminal block takes a glanded cable directly.
The loop hunts near the closed position
Check the spring range against the 20-100 kPa requirement before adjusting anything, because an open-loop transducer cannot correct a selection error.
Features And Specifications
Every figure below is transcribed from the datasheet EAA publishes for this series. Anything not published is not listed.
- 4-20 mA input (code A)
- 3-15 psig, 0.20-1.0 BAR output (code C)
- Terminal block electrical connection (code T)
- Miniature 550 series body
- External span and zero adjustment
- ATEX and 1/4 inch BSP porting available as options
| Code | Input signal |
|---|---|
| A | 4-20 mA |
| C | 0-5 VDC |
| D | 1-9 VDC |
| E | 0-10 VDC |
| F | 1-5 VDC |
| Code | Output psig | Output BAR |
|---|---|---|
| C | 3-15 psig | 0.20-1.0 BAR |
| D | 3-27 psig | 0.20-1.8 BAR |
| E | 6-30 psig | 0.40-2.0 BAR |
| G | 2-60 psig | 0.14-4.0 BAR* |
| H | 3-120 psig | 0.20-8.0 BAR* |
| I | 0-30 psig | 0.00-2.0 BAR |
| J | 0-60 psig | 0.00-4.0 BAR |
| K | 0-120 psig | 0.00-8.0 BAR |
| Code | Electrical connection |
|---|---|
| A | 1/2 inch NPT conduit with pigtail |
| D | DIN 43650 connector |
| T | Terminal block |
| Code | Option |
|---|---|
| K | ATEX approvals, 4-20 mA only, voids FM and CSA approvals |
| U | 1/4 inch BSP porting |
| Accessory | Kit number |
|---|---|
| DIN rail mounting kit | Kit No. 445-766-024 |
| 1.5 inch or 2 inch pipe mounting kit | Kit No. 448-542-005 |
Output is calibrated at the factory. The large span adjustment range allows recalibration to 3-35 psig (0.2-2.4 BAR) on the 2-60 psig unit and up to 3-145 psig (0.2-10.0 BAR) on the 3-120 psig unit.
Selecting Installing And Calibrating
- Read the code before fitting550-A-C-T tells you the input, the output and the termination. Check all three against the loop drawing.
- Land the cableTerminate into the terminal block and confirm polarity before energising the loop.
- Feed clean airThe instrument air into the transducer has to be steady and dry. A filter regulator on the inlet is part of the installation, not an accessory.
- Set the two points4 mA to the bottom of the output range, 20 mA to the top, then confirm the valve strokes fully in both directions.
How It Compares With The Alternatives
The ACT and the 550X are the same series: the 550X is the coding system, the ACT is one build from it. Against the 500AC, which is the same electrical and pneumatic pairing, the ACT is physically smaller and terminates on a block rather than a pigtail.
| Model | Distinguishing specification | Best suited to |
|---|---|---|
| 550ACT Electro Pneumatic Transducer | 4-20 mA, 3-15 psig, terminal block | Standard loops in tight spaces |
| 550X Electro Pneumatic Transducer | Full coding system, eight output ranges | Non-standard ranges and approvals |
| 500AC Electro Pneumatic Transducer | Same ranges, full-size body | Conventional mounting with room to spare |
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View specifications →Questions About The 550ACT Electro Pneumatic Transducer
What do the letters A, C and T mean
A is the 4-20 mA input signal, C is the 3-15 psig (0.20-1.0 BAR) output and T is the terminal block electrical connection, all from the published 550 coding table.
Can I get the same unit with a DIN connector
Yes. Change the last letter from T to D for a DIN 43650 connector, or to A for a 1/2 inch NPT conduit with pigtail.
What output ranges are available if 3-15 psig is wrong
Codes D, E, G and H give 3-27, 6-30, 2-60 and 3-120 psig, and codes I, J and K give the zero-based 0-30, 0-60 and 0-120 psig ranges.
Is the output calibrated at the factory
Yes, and the large span adjustment allows recalibration from 3-35 psig on the 2-60 psig unit up to 3-145 psig on the 3-120 psig unit.
Can it be DIN rail mounted
Yes, with kit 445-766-024. A 1.5 inch or 2 inch pipe mounting kit, 448-542-005, is also available.
Request A Price For The 550ACT
Tell us the input signal, the output range and the electrical termination, and the quotation comes back against the published part number.