Data Sheet

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Fisherr 546 Electro‐Pneumatic Transducer

Fisher 546 transducers receive a direct‐current input

signal and use a torque motor, nozzle‐flapper, and

pneumatic relay to convert the signal to a proportional

pneumatic output signal. Nozzle pressure, which

operates the relay, is also piped to the torque motor

feedback bellows. This provides a comparison

between input signal and nozzle pressure and reduces

errors in nozzle pressure.

The transducer can be mounted on a pneumatic

diaphragm control valve actuator to provide accurate

operation of the valve. The integrated high‐capacity

pneumatic relay eliminates the need for additional

boosters or relays for operation of control valves.

The transducer also can be used to provide stable

operation when its output signal is transmitted to

small terminal volume chambers such as control

bellows in pneumatic valve positioners.

Features

n Vibration Resistance—High natural frequency of

torque motor moving parts results in negligible

vibration influence.

n Easy Adjustment—Screwdriver adjustments for span

and zero are conveniently located and have arrows

indicating rotation to increase settings (as shown in

figure 1).

W2115

Fisher 546 Transducer Mounted on

657 Pneumatic Diaphragm Actuator

n Field‐Reversible Action—No additional parts

required to reverse action.

n Simple Relay Removal—Integrated pneumatic relay

is mounted outside case and can be removed

without disturbing electrical or pressure

connections or impairing explosion safety.

546 Transducer

D200061X012

Product Bulletin

62.1:546

September 2012

Summary of content (8 pages)

PAGE 1
Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X012 Fisherr 546 Electro‐Pneumatic Transducer Fisher 546 transducers receive a direct‐current input signal and use a torque motor, nozzle‐flapper, and pneumatic relay to convert the signal to a proportional pneumatic output signal. Nozzle pressure, which operates the relay, is also piped to the torque motor feedback bellows. This provides a comparison between input signal and nozzle pressure and reduces errors in nozzle pressure.
PAGE 2
Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X012 Specifications Available Configuration Electro‐pneumatic signal transducer with explosion‐proof case and cover The 546 can ordered J with or J without a Fisher 67CFR filter regulator.
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Product Bulletin 546 Transducer 62.
PAGE 4
Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X012 Principle of Operation Refer to figure 2, and assume that the transducer is direct acting. As the DC milliamp signal increases, so does the magnetic field around the coils. This results in an increased magnetic attraction between the armature and the pole pieces. The armature rotates slightly clockwise to cover the nozzle, increasing pressure in the nozzle, the upper chamber of the relay, and the feedback bellows.
PAGE 5
Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X102 Valve Stroking Time Installation Figure 3 shows relative times for loading and exhausting an actuator. Exhausting times are nominally 25 percent of the loading times. Stroking time depends upon the size of the actuator, travel, relay characteristics and the magnitude and rate of change of the input signal. If stroking time is critical, contact your Emerson Process Management sales office.
PAGE 6
Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X012 Figure 4. Dimensions 1/4 NPT SUPPLY CONNECTION WHEN FILTER REGULATOR IS FURNISHED 329 (12.94) 1/4 NPT OUTPUT CONNECTION 78 (3.06) 125 (4.94) 171 (6.75) 52 (2.06) 46 (1.81) 43 (1.69) 67 (2.62) 40 (1.56) 51 (2.00) 32 (1.25) 164 (6.44) 44 (1.75) 165 (6.50) 83 (3.25) 22 (0.88) 70 (2.75) 1/2 NPT CONDUIT CONNECTION 51 PIPE (2.00) CP7280-E A1249-1 51 (2.
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Product Bulletin 546 Transducer 62.1:546 September 2012 D200061X102 Table 1.
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Product Bulletin 62.1:546 September 2012 546 Transducer D200061X012 Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user. Fisher is a mark owned by one of the companies in the Emerson Process Management business unit of Emerson Electric Co.