UL Approval Canadian Standards Association Atmosphères ExplosiblesEuropean ConformityIECEx Approval


  • Fully-Approved Explosion-Proof Loop-Powered Meters
  • 4-20 mA Input with ±0.05% Accuracy of Calibrated Span
  • 1.7 Volt Drop (4.7 Volt Drop with Backlight)
  • Easy Field Scaling in Engineering Units without a Calibrator
  • 0.6" (15.2 mm) 3½+ Digits LCD Display; -1999 to 2999
  • Display Mountable at 0°, 90°, 180°, & 270°
  • HART® Protocol Transparent
  • Loop-Powered Backlight
  • Operating Temperature Range: -40 to 75°C (-40 to 167°F)
  • Installation Temperature Range: -55 to 75°C (-67 to 167°F)
  • Four Internal Buttons for Easy Field Scaling
  • Max/Min Display
  • Programmable Noise Filter
  • 32-Point Linearization & Square Root Extraction
  • Conformal Coated PCBs for Dust & Humidity Protection
  • UL Listed as Explosion-Proof / Dust Ignition-Proof / Flame-Proof
  • CSA Certified as Explosion-Proof / Dust Ignition-Proof / Flame-Proof
  • ATEX and IECEx Certified as Explosion-Proof
  • Built-In Flange for Wall or Pipe Mounting
  • Explosion-Proof, IP68, NEMA 4X Die-Cast Aluminum & Stainless Steel Enclosures
  • Two 1/2" NPT or M20 Conduit Openings
  • 1.5" U-Bolt Kit & 2" Pipe Mounting Kit Available
  • Stainless Steel Tag Available
  • 3-Year Warranty

Why Use Loop-Powered Meters?

The most basic decision a user wishing to display a 4-20 mA signal on a digital display has to make is: should the meter be powered by line voltage or should it be powered by the 4-20 mA loop?

There are three main benefits of using loop-powered devices:

  • No additional power required
  • Easy wiring
  • Additional digital displays can easily be added in the same loop

The following diagram illustrates how a loop-powered meter is wired. Notice there are only two connections made to the meter.

For more information on loop-powered meters, check out Fundamentals of Loop-Powered Devices and Loop-Powered vs Line-Powered Meters white papers.


The PD663 is an explosion-proof loop-powered field meter that is available in an aluminum or stainless steel enclosure.

The ProtEX-Lite carries all major approvals including:

  • UL Listed as Explosion-Proof / Dust Ignition-Proof / Flame-Proof
  • CSA Certified as Explosion-Proof / Dust Ignition-Proof / Flame-Proof
  • ATEX and IECEx Certified as Explosion-Proof

The PD663 is easy to install and program and the display can be seen in a variety of lighting conditions, even in bright sunlight. It will operate down to -40°C and is approved for installation in areas where the temperature gets as cold as -55°C, however the display will cease functioning.

The fact that this meter is loop-powered means that there is no need to run additional, costly power lines into a hazardous area. The meter gets all the power it needs from the 4-20 mA loop and its 1.7 V drop results in a minimal burden on the loop. Loop-powered backlighting is a standard feature that allows the meter to be read in dimly lit areas.

The meter features a built-in flange for wall or pipe mounting. Calibration is a quick process involving the four internal pushbuttons. The 3½+ digits display on the ProtEX-Lite will read up to 2999.

Physical Features

ProtEX-Lite Enclosures

PD663 Callout Features

PD663 Great in Cold Temperatures

Great for Cold Temperatures

The ProtEX-Lite PD663 will operate over a temperature range of -40 to 75°C (-40 to 167°F). Below -40°C, the display will cease functioning, however, the instrument is approved to be installed in locations where the temperature goes down to -55°C.

PD663 Electronics Module

Electronics Module

The ProtEX-Lite electronics module is housed in a plastic enclosure that provides a degree of environmental protection for the electronics circuitry. The module is mounted to the enclosure with spring-loaded thumbscrews and can be oriented in 0°, 90°, 180°, or 270° increments. Connections are made to a removable screw terminal block.

PDA6631-SS 1.5 inch U-Bolt Kit

PDA6631-SS 1.5" U-Bolt Kit

PDA6863-SS Pipe Mounting Kits

PDA6863-SS 2" Pipe Mounting Kit

Easy Pipe Mounting

The ProtEX-Lite comes with cast-in mounting flanges. These allow easy mounting to walls or pipes us-ing the PDA6631-SS Stainless Steel U-Bolt Kit for a 1.5” pipe or the PDA6863-SS Stainless Steel Pipe Mounting Kit for a 2” pipe. A slot on the back of the enclosure makes it easy to center the unit on a pipe.

PD663 Display Not Rotated
PD663 Display Rotates in 90° Increments

Rotatable Display Module

The display module can be rotated in 90° increments providing added mounting flexibility. Plus the various conduit connections allow a variety of installation options.

Tamper-Proof Wire and Seal for PD663

Tamper-Proof Capability

The instrument can be made tamper-proof by inserting a wire through the built-in loop on the base of the enclosure and a hole in the lid of the enclosure and securing this wire with a lead seal.

Stainless Steel Attaching Loop on PD663

Stainless Steel Tag Attaching Loop

The enclosure is equipped with a loop at the top to easily attach a PDA-SSTAG stainless steel tag.


The PD663 comes calibrated and scaled at the factory to display a 4.00 to 20.00 mA signal on startup. To change the scaling, follow along using the 4 button interface.

Programming the PD663


Display0.6" (15.2 mm) LCD, 3½+ digits;
-1999 to 2999
Loop-Powered BacklightPowered directly from the 4-20 mA loop, no batteries required. Backlight can be enabled or disabled via alternative wiring of terminal block. The display brightness will increase as the input signal current increases.
Display Update Rate2 Updates/Second
Display OrientationDisplay may be mounted at 90° increments up to 270° from default orientation.
OverrangeDisplay flashes 2999
UnderrangeDisplay flashes -1999
Programming Method4 Internal pushbuttons (behind glass)
Noise FilterProgrammable HI, LO, or OFF
RecalibrationRecalibration is recommended at least every 12 months.
Max/Min DisplayMax/Min readings reached by the process are stored until reset by the user or until power to the meter is turned off.
Non-Volatile MemoryAll programmed settings are stored in nonvolatile memory for a minimum of ten years if power is lost.
Normal Mode Rejection64 dB at 50/60 Hz
EnvironmentalOperating temperature range: -40 to 75°C
Storage temperature range: -40 to 75°C
Installation temperature range: -55 to 75°C
Relative humidity: 0 to 90% non-condensing
Printed circuit boards are conformally coated.
ConnectionsScrew terminals accept 12 to 22 AWG wire
MountingMay be mounted directly to conduit.
Two mounting holes for 1.5" pipe or wall mounting.
Tightening TorqueScrew terminal electrical connectors: 4.5 lb-in (0.5 Nm)
Overall Dimensions4.30" x 4.27" x 3.66"
(109 mm x 108 mm x 93 mm)
(W x H x D)
WeightAluminum Models: 2.45 lbs (40 oz, 1.13 kg)
Stainless Steel Models: 5.00 lbs (80 oz, 2.3 kg)
Warranty3 years parts and labor. See Warranty Information and Terms & Conditions on www.predig.com for complete details.


Input4-20 mA
Accuracy±0.05% of calibrated span ±1 count
FunctionLinear (2 to 32 points) or square root
Temperature Drift50 PPM/°C from -40 to 75°C ambient
Decimal PointUser selectable decimal point
Minimum SpanInput 1 & Input 2: 0.40 mA
Calibration RangeAn Error message will appear if input 1 and input 2 signals are too close together.
Input Range
4-20 mA
Minimum Span Input 1 & Input 2
0.40 mA
Maximum Voltage Drop & Equivalent ResistanceWithout BacklightWith Loop Powered Backlight
1.7 VDC @ 20 mA4.7 VDC @ 20 mA
85 Ω @ 20 mA235 Ω @ 20 mA
Input OverloadOver current protection to 2 A max.
HART TransparencyThe meter does not interfere with existing HART communications; it displays the 4 20 mA primary variable and it allows the HART communications to pass through without interruption.
The meter is not affected if a HART communicator is connected to the loop.
The meter does not display secondary HART variables.


MaterialAL Models: ASTM A413 LM6 die-cast aluminum, copper-free, enamel coated
SS Models: ASTM A743 CF8M investment-cast 316 stainless steel
Gasket (O-Ring)Fluoroelastomer
RatingNEMA 4X, IP68 Explosion-proof
ColorAluminum Models: Blue
Stainless Steel Models: Silver
WindowBorosilicate glass
ConduitsPD663-0K0-00: Two 1/2" NPT
PD663-0K0-00-M20: Two M20
FlangeBuilt-in flange for wall and pipe mounting.
Tamper-Proof SealCover may be secured with tamper-proof seal.

Product Ratings and Approvals

ULExplosion-Proof for use in:
      For Class I, Division 1, Groups B, C, D
      Class II, Division 1, Groups E, F, G
      Class III, Division 1; T6
      Class I, Zone 1, AEx db IIC T6 Gb
      Zone 21, AEx tb IIIC T85°C Db
      Tamb = -55°C to 75°C
      UL Type 4X, IP66 / IP68
      UL File Number: E494837
CSAExplosion-Proof for use in:
      Class I, Division 1, Groups B, C and D
Dust Ignition-Proof for use in:
      Class II/III, Division 1, Groups E, F and G; T6
Flame-Proof for use in:
      Zone 1, Ex d IIC T6
      Ta = -55 to 75°C.
      Enclosure: Type 4X & IP66/IP68
      Certificate Number: CSA 11 2325749
ATEXExplosion-Proof for use in:
      ATEXII 2 G D
      Ex db IIC T6 Gb
      Ex tb IIIC T85°C Db IP68
      Ta = -55 to 75°C
      Certificate Number: Sira 10ATEX1116X
IECExExplosion-Proof for use in:
      Ex db IIC T6 Gb
      Ex tb IIIC T85°C Db IP68
      Ta = -55 to 75°C
      Certificate Number: IECEx SIR 10.0056X


PD663 Dimensions - Front

Front View

PD663 Dimensions - Side

Side View

PD663 Dimensions - Top

Top View

PD663 CAD Drawings


PD663 Connector Labeling

Connectors Labeling

Wiring Diagrams

For existing applications, one of the great benefits of loop-powered meters is that they get their power directly from the 4-20 mA loop and thus require no additional wiring. All a user has to do is break the existing loop and wire in the meter.

PD663 Connections with Backlight

4-20 mA Input Connection with Backlight

PD663 Connections without Backlight

4-20 mA Input Connection without Backlight


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