YOKOGAWA MLD User manual

IM 61A01A01-01E-A
4th Edition
User’s
Manual
IM 61A01A01-01E-A
Model MLD
Loop Powered Process Indicator

IM 61A01A01-01E-A
Model
Suffix Codes
Description
MLD
Field Mounted Loop Indicator (Digital)
Input Signal
-A
4 to 20 mA DC
Mounting
1
2
2” Horizontal Pipe
2” Vertical Pipe (or wall mount)
Housing
/1
/2
Cast Aluminum Alloy - (Standard Housing)
SUS316 Cast Stainless Steel and ASTM CF-8M
Electrical
Connection
/00
/20
/30
/40
ANSI ½ NPT female, without blind plug
ANSI ½ NPT female, 316 Stainless Steel blind plug
ISO M20 female, without blind plug
ISO M20 female, 316 Stainless Steel blind plug
Ex Protection
/FF1
/CF1
FM Explosion Proof
CSA Explosion Proof
Optional Specifications
Coating
/X1
/X2
Epoxy resin coating
Polyurethane-Epoxy Anti-corrosion coating
Paint
/P1
/P2
/P3
/P4
/P5
/P6
/P7
Light Blue (RAL # 5012)
Orange (RAL # 2008)
Red (Munsell # 7.5 R4/14)
Mint Green
Silver (RAL # 9006)
Yellow (RAL # 1018)
Gray (RAL # 7046)
Calibration
/ENG
Engineering Unit Calibration (MLD Only)
Stainless Steel Tag
/SST
/SSW
Stainless Steel tag screw attached to housing
Stainless Steel tag wired to housing
Stainless Steel Tag
/SSW
Stainless Steel tag wired to housing
1. PREFACE
The Model MLD field mounted indicator receives a DC current signal from electronic transmitters and
indicates process measurement values. This instruction manual gives instructions on handling, mounting,
and wiring of the MLD indicator.
2. MODEL CODE AND SPECIFICATIONS
STANDARD SPECIFICATIONS
Voltage Drop:
1.8V typ., 2V max.
Scale:
0 - 1999 w/decimal
Accuracy:
± 0.05% of full scale (1999) ±1 count
Operating Temperature Range:
-20 to 60°C
Temperature drift: ±0.3 Count/°C
Insulation Resistance: Between input
terminals and case 100 Mohm at 500 V DC
Dielectric Strength: Between input terminals
and case: 1000 VAC for 1 minute.
Mounting: Nominal 2” (50mm) pipe mount or
surface.
Explosion Protection Type : FM, CSA,
EXPLOSIONPROOF CL1, DIV1, GROUPS
A,B,C,D, DUST-IGNITIONPROOF CLII / III,
GROUPS E,F,G
Case and Cover: Die cast aluminum or 316
Stainless Steel, baked polyurethane paint. Moss
Green (Stainless Steel is unpainted); NEMA 4X
Electrical Connection: ½ x 14 NPT or
M20 x 1.5
Weight: 2.7 lbs
ORDERING INSTRUCTIONS
1. Model and Suffix codes.
2. Option Codes
Example Ordering Instructions:
MLD-A1/1/00/FF1/ENG/SST Field Mounted Indicator (Digital), 4 to 20 mA DC, 2” Horizontal Pipe, FM Explosion Proof
0-200 InH2O Scale in Engineering Units. Please specify Scale and Engineering units when ordering /ENG
FT-201 Specify Tag Number when ordering /SST or /SSW

IM 61A01A01-01E-A
DIMENSIONS
3. INSTALLATION
The Loop Powered Indicator can be mounted on a wall or a 2” pipe. The housing is a NEMA 4X Explosion Proof housing so it can be mounted
outside in the field.
Do not install the unit in the following conditions:
• Extreme Temperatures beyond the temperature rating of the instrument.
• High vibration areas above the vibration rating of the instrument.
• Extremely corrosive environments.
MOUNTING EXAMPLES

IM 61A01A01-01E-A
4. WIRING
The loop powered indicator series is powered by the current output loop and does not require external power. All devices must be wired in series
with the current loop. Twisted pair shielded cable is recommended.
The following is an example of the MLD Loop Indicator connected to an EJA Pressure Transmitter (Note: The EJA Transmitter below can be
replaced with any 4-20mA 2 wire device.)
The Loop Indicator is available in FM Explosion Proof and CSA Explosion Proof types for hazardous locations. Wire sealing is required for these
approvals. The following diagrams show some wire sealing examples.
For Flameproof type, use Flameproof Packing Adapter or Flameproof Conduit in connection above.

IM 61A01A01-01E-A
MOUNTING IN HAZARDOUS LOCATIONS

IM 61A01A01-01E-A
5. CALIBRATION
Calibration of MLD Units
(1) The MLD model ships with a calibration range of 0-100% unless ordered with the /ENG
Engineering Units option.
(2) If adjustments are needed the 2 screws holding the plate will need to be removed
(3) Connect unit to a Current Standard (red to +, black to -). Current Standards can be purchased
through Yokogawa Corporation of America. Recommended models are CA310 (Voltage/Current
Calibrator) or CA71 (Multifunction Calibrator).
(4) Set range switches based on the following table (for standard 0-100% unit set SW1 and SW8 to
ON):
Desired Display Reading
4mA
Adjustment
20mA
Adjustment
Minimum
20mA
Adjustment
Maximum
SW1
SW2
SW3
SW4
SW5
000
1200
1999
OFF
OFF
OFF
OFF
OFF
000
600
1200
ON
OFF
OFF
OFF
OFF
000
400
600
OFF
OFF
ON
OFF
OFF
000
200
400
ON
ON
ON
OFF
OFF
000
100
200
ON
ON
ON
ON
OFF
(5) Set the Decimal value as follows:
a. If tenths (ex. XXX.X) set SW8 on.
b. If hundredths (ex. XX.XX) set SW7 on.
c. If thousandths (ex. X.XXX) set SW6 on.
(6) The values to check are shown in the table below.
(7) Set the Current standard to the 0% value. Adjust the Zero Pot (top one) to read the minimum value
needed.
(8) Set the Current Standard to the 100% value. Adjust the Span Pot (bottom one) to read the
maximum value needed.
(9) Check all points in the table above and verify unit is within specification.
Suffix –A
4-20mA
0%
4.0mA
25%
8.0mA
50%
12mA
75%
16mA
100%
20mA

IM 61A01A01-01E-A
6. ROTATING DISPLAY DIRECTION
The loop indicator display is designed so that it can be rotated in 90 degree increments. This is
accomplished by ordering the unit as a horizontal pipe mount or a vertical pipe mount. However there
may be the need for the customer to change the angle of the display. The following are procedures for
the display rotation:
Display Rotation:
(1) Remove power from the unit.
(2) Remove the glass cover from the display side.
(3) Remove the 2 screws holding the mounting plate to the standoffs.
(4) Rotate the display to the desired position (can be rotated in 90 degree increments).
(5) Replace and tighten firmly the 2 screws into the standoffs.
(6) Replace the glass cover.