Emerson Fisher 546 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

546 Transducer

D200061X012

Product Bulletin

62.1:546

September 2012

2

Specifications

Available Configuration

Electro‐pneumatic signal transducer with

explosion‐proof case and cover

The 546 can ordered Jwith or Jwithout a Fisher

67CFR filter regulator. The 51 mm (2 inch) supply

pressure gauge mounted on the regulator may be

J0 to 30 psig or J0 to 60 psig range

Input Signals

J4 to 20 mA DC, J10 to 50 mA DC, J1 to 9 V DC,

or JTwo‐way split range using either half of one of

the standard input signal spans

Internal Resistance of Torque Motor

4 to 20 mA DC Input Signal: 176 ±10 ohms

10 to 50 mA DC Input Signal: 90 ±10 ohms

1 to 9 VDC Input Signal: 1300 ±50 ohms

(temperature compensated circuit)

Output Signals

Ranges:

J0.2 to 1.0 bar (3 to 15 psig), J0.4 to 2.0 bar

(6 to 30 psig), J 0 to 1.2 bar (0 to 18 psig) or

J0 to 2.3 bar (0 to 33 psig)

Action: Field-reversible between Jdirect and

Jreverse

Supply Pressure(1)

Recommended: 0.3 bar (5 psi) higher than upper

range limit of output signal

Maximum: 3.5 bar (50 psig)

Average Steady‐State Air Consumption(2)(3)

0.44 m3/hr (16.5 scfh) at 1.4 bar (20 psi) supply

pressure

Maximum Output Air Capacity(2)

At 1.4 bar (20 psig) Supply Pressure:

12.9 m3/hr (480 scfh)

At 2.4 bar (35 psig) Supply Pressure:

18.5 m3/hr (690 scfh)

Performance(4)

Actuator Loading Time: see figure 3

Reference Accuracy: ±0.75% of output signal span

Independent Linearity: ±0.50% of output signal span

Open Loop Gain: 26

Frequency Response: Gain is attenuated 3 dB at 20 Hz

with transducer output signal piped to a typical

instrument bellows with 305 mm (12 inch) of 1/4 inch

tubing

Electromagnetic Interference (EMI): Tested per IEC

61326‐1 (Edition 1.1). Meets emission levels for Class

A equipment (industrial locations) and Class B

equipment (domestic locations). Meets immunity

requirements for industrial locations (Table A.1 in the

IEC specification document). Immunity performance

shown in table 1.

Operative Ambient Temperature Limits(1)

-40 to 66_C (-40 to 150_F)

Electrical Classification

Hazardous Area:

CSA—Explosion-proof, Dust Ignition‐proof, Div 2

FM—Explosion‐proof, Non‐incendive

Refer to table 2 for specific approval information.

NEMA 3R, CSA Enclosure 3

NEMA 3R mounting orientation requires vent location

to be below horizontal.

Adjustments

Zero and Span Adjustments: Screwdriver adjustments

located inside case (see figure 1)

Connections

Supply Pressure: 1/4 NPT internal located on side of

case (located on filter‐regulator if a 67CFR is mounted

to transducer)

Output Pressure: 1/4 NPT internal located on side of

case

Vent: 1/4 NPT internal with screen located on relay

Electrical: 1/2 NPT internal located on bottom of case

-continued-

546 Transducer

D200061X102

Product Bulletin

62.1:546

September 2012

3

Specifications (continued)

Construction Materials

Case and Cover: Aluminum

O‐Rings: Nitrile

Flame Arrestors: Stainless steel

Supporting Bracket/Torsion Member: Stainless steel

Magnets: Alloy steel

Nozzle: Stainless steel

Feedback Bellows: Brass

Relay Body: Aluminum

Relay Restriction: Aluminum/Stainless steel

Relay Diaphragm: Nitrile

Relay Valve Plug and Seat Ring: Brass

Mounting

Mounting parts are available for Jcontrol valve

actuator mounting, Jpipestand (2 inch nominal)

mounting, or Jsurface mounting

Approximate Weight

4.1 kg (9 lb)

NOTE: Specialized instrument terms are defined in ANSI/ISA Standard 51.1 - Process Instrument Terminology.

1. The pressure/temperature limits in this document and any applicable standard or code limitation should not be exceeded.

2. Normal m3/hr-‐Normal cubic meters per hour (0_C and 1.01325 bar, absolute). Scfh‐‐Standard cubic feet per hour (60_F and 14.7 psia).

3. Average flow rate determined at 12 mA and 0.6 bar (9 psig) output.

4. Performance values are obtained using a transducer with a 4 to 20 mA DC input signal and a 0.2 to 1.0 bar (3 to 15 psig) or a 0.4 to 2.0 bar (6 to 30 psig) output signal. Ambient temperature is 24_C

(75_F). A transducer with other input or output signals may exceed these values.

Figure 1. Zero and Span Adjustments (Cover Removed)

W5391

ZERO ADJUSTMENT

SPAN ADJUSTMENT

546 Transducer

D200061X012

Product Bulletin

62.1:546

September 2012

4

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. Increased nozzle pressure

and increased pressure in the upper chamber of the

relay cause the relay supply port to open, increasing

the output pressure to the actuator and the control

valve. At the same time, the increased pressure in the

feedback bellows acts to move the armature back to

the equilibrium position. In this way, the new nozzle

pressure is compared to the DC input signal by the

force balance principle.

As the DC input signal decreases, magnetic attraction

is reduced and the armature rotates slightly in the

counterclockwise direction to uncover the nozzle.

Decreased nozzle pressure and decreased pressure in

the upper chamber of the relay cause the relay exhaust

port to open and allow output pressure to bleed to

atmosphere. Pressure to the control valve is reduced

until equilibrium is attained.

Reverse‐acting transducers operate in a similar

manner except that when the DC input signal

increases, pressure to the actuator and control valve

decreases.

Figure 2. Transducer Schematic

FEEDBACK

BELLOWS

POLE PIECES

COIL

ARMATURE

TORSION ROD

EXHAUST

OUTPUT

RELAY

VALVE PLUG

SUPPLY

FIXED RESTRICTION

CENTER SPACER ASSEMBLY

EXHAUST PRESSURE

SUPPLY PRESSURE

NOZZLE PRESSURE

OUTPUT PRESSURE

NOZZLE

ARMATURE

PERMANENT MAGNET

ZERO ADJUSTMENT

SPAN ADJUSTMENT

(MAGNETIC SHUNT)

CP4285-A

A1505-3

546 Transducer

D200061X102

Product Bulletin

62.1:546

September 2012

5

Valve Stroking Time

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.

Figure 3. Output‐Time Relationship

LOADING

EXHAUSTING

TIME (%)

0 102030405060708090100

0

10

20

30

40

50

60

70

80

90

100

OUTPUT

(% OF 546 OUTPUT SPAN)

19A1361‐A

A3103

Installation

Standard positions for actuator mounting and

pipestand mounting are shown on the front cover

and figure 4, respectively. Dimensions are shown in

figure 4.

Ordering Information

To determine what ordering information is required,

refer to the Specifications table. Carefully review the

information under each specification and in the

referenced table. Specify the desired choice wherever

there is a selection to be made. Always specify the type

number as identified in the Available Configurations

specification.

For transducers that are to be used in intrinsically safe

installations, specify the rating required and the

system with which the unit will be used.

When ordering actuator mounting parts, specify the

actuator type, size, travel, and diaphragm pressure

range. For all Fisher 657 and 667 actuators except size

80, specify whether actuator yoke or actuator casing

mounting is desired (yoke mounting is only available

on size 80 actuators).

For split‐range operation, specify the portion of input

signal to be used; e.g. 4 to 12 milliamps of a standard

4 to 20 milliamp signal.

546 Transducer

D200061X012

Product Bulletin

62.1:546

September 2012

6

Figure 4. Dimensions

51

(2.00)

CP6477-E

A1248-1

ACTUATOR MOUNTING

16

(0.62)

56

(2.25)

70

(2.75) 37

(1.44)

70

(2.75)

22

(0.88)

1/2 NPT CONDUIT

CONNECTION

329

(12.94)

78

(3.06)

125

(4.94)

46

(1.81)

32

(1.25)

83

(3.25)

164

(6.44)

40

(1.56)

44

(1.75)

8.7

(0.34)

1/4 NPT OUTPUT

CONNECTION

51

(2.00)

CP7280-E

A1249-1 PIPESTAND MOUNTING

51 PIPE

(2.00)

165

(6.50)

70

(2.75)

22

(0.88) 1/2 NPT CONDUIT

CONNECTION

329

(12.94)

78

(3.06)

125

(4.94)

46

(1.81)

32

(1.25)

83

(3.25)

164

(6.44)

40

(1.56)

44

(1.75)

1/4 NPT

OUTPUT

CONNECTION

51

(2.00)

1/4 NPT SUPPLY

CONNECTION

WHEN FILTER

REGULATOR

IS FURNISHED

67

(2.62)

1/4 NPT SUPPLY

CONNECTION

WHEN FILTER

REGULATOR

IS NOT FURNISHED

171

(6.75)

52

(2.06)

43

(1.69)

37

(1.44)

40

(1.56)

6.3

(0.25)

mm

(INCH)

546 Transducer

D200061X102

Product Bulletin

62.1:546

September 2012

7

Table 1. Electromagnetic Immunity Performance

Port Phenomenon Basic Standard Test Level Performance Criteria(1)

Enclosure

Electrostatic discharge (ESD) IEC 61000‐4‐2 4 kV contact

8 kV air A

Radiated EM field IEC 61000‐4‐3 80 to 1000 MHz @ 10V/m with

1 kHz AM at 80% A

Rated power frequency magnetic field IEC 61000‐4‐8 60 A/m at 50 Hz A

I/O signal/control

Burst (fast transients) IEC 61000‐4‐4 1 kV A

Surge IEC 61000‐4‐5 1 kV (line to ground only, each) B

Conducted RF IEC 61000‐4‐6 150 kHz to 80 MHz at 3 Vrms

with 1kHz AM at 80% A

Specification limit = ±1% of span

1. A=No degradation during testing. B = Temporary degradation during testing, but is self‐recovering.

Table 2. Hazardous Area Classifications—CSA (Canada)

Certification Body Certification Obtained Temperature Code Enclosure Rating

CSA

Explosion-proof

Class I, Division 1, Group C,D T5 (Tamb = 66_C) CSA ENC 3

Class II, Division 1, Groups E,F,G

Class I, Division 2, Groups A,B,C,D

Class II, Division 2, Groups F,G

T5 CSA ENC 3

Table 3. Hazardous Area Classifications—FM (United States)

Certification Body Certification Obtained Temperature Code Enclosure Rating

FM

Explosion-proof

Class I, Division 1, Groups C,D T5 (Tamb = 60_C) NEMA 3R

Class II, Division 1, Groups E,F,G

Class I, Division 2, Groups A,B,C,D

Class II, Division 2, Groups F,G

T5 NEMA 3R

546 Transducer

D200061X012

Product Bulletin

62.1:546

September 2012

8

Emerson Process Management

Marshalltown, Iowa 50158 USA

Sorocaba, 18087 Brazil

Chatham, Kent ME4 4QZ UK

Dubai, United Arab Emirates

Singapore 128461 Singapore

www.Fisher.com

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