Murphy MDM45 User Manual

Digital Loop Monitor SWICHGAGE

SWICHGAGE

®

®

Model MDM45

3 Instruments in 1

•

Monitor Any 4–20 mA

Approved

Approved

*

*

•

Linear Output
Designed to Operate

•

from 12–24 VDC
Adjust a Separate Trip Point

•

for High and Low Values
Easy Access for Trip Point,

•

Span and Zero Adjustments
Specify Unit of

•

Measurement

Approved for 10–30 VDC power input and

*

4–20 mA signal input.

®

MDM-9113B

Revised 01-98

Catalog Section 05

(00-02-0027)

Description

Model MDM45 is an electronic LOOP MONITOR which
accepts one 4–20 mA transmitter input and digitally dis­plays the results via a highly visible Liquid Crystal Display.
Separately adjustable high and low limit trip points are also
provided for control functions. Atoggle switch and push but­ton on the face allow the operator to select the trip point to
be read and set. Both trip points are always active regard­less of the position of the toggle switch.

Designed to be installed within a weatherproof enclosure the
MDM45 can be panel mounted in the same manner as our
popular OPL and SPL series SWICHGAGE®instruments.
Zero and span adjustments are easily accessible from the
face of the MDM45 for setting to the 4–20 mA input signal.

Features

The model MDM45 is designed to operate from 12 or 24
VDC (10-30 VDC) systems. This model has FET trip point
outputs. The “Push to Read” button allows the operator to
check each trip point value and to watch the display as
adjustments are made to a selected trip point. Releasing the
push button returns the readout to that equal to the input
signal: i.e. pressure, level, percent open, etc. The user
determines the unit of measurement according to the source
of the input signal. An LED below the trip point adjustment
potentiometer lights to indicate that the trip point has been
reached.

Added value from basic features. (1) Onboard DC to DC
conversion for superior interference isolation. (2) Front
accessible span and zero adjustment. (3) Easy to read one­half inch numerals on a liquid crystal display. (4) Three instru­ments in one: digital gauge, low limit switch, high limit switch.
(5) Extremely user friendly and highly field adaptable.

Applications

Engine/compressor lube-oil pressures

•

Pump/compressor discharge pressures

•

Valve position indication (% open/closed)

•

Vibration

•

Any 4–20 mA input

•

Specifications

Accuracy: ± 1% of full scale.
Operating Temperature Range: 32 to 155°F (0 to 70°C).
Storage Temperature: -40 to 300°F (-40 to 150°C).
Display Range: -10,000 to 19,999.
Signal Input: 4–20 mA.
Input Resistance: 250 Ohms.
Display Update Time: 0.5 seconds.
Power: 1.8 watts @ 12 VDC

3.6 watts @ 24 VDC.

min.-max. operating voltage 10–30 VDC.

Trip Point Output:A power FET switch turns on when

signal reaches the trip point. Trip points can be selected
to open or closed (0.5 amp @ 250 VDC).

Shipping Weight: 2 lb. 7 oz. (1.2 kg).
Shipping Dimensions: 10 x 9 x 6 in. (254 x 229 x 152 mm).

Laboratory Approvals: CSA and FM approved†for Class

I, Division 2, Group D, hazardous locations).

†

Approved for 10–30 VDC power input and 4–20 mA signal input.

About Trip Points

During normal operation, both trip points are always active
and are independent of the trip point selector switch.

When the transmitter signal meets the high or low trip
point, that trip point is triggered: the trip point output “turns
on”; and an LED lights to indicate the output is ON.

Dimensions

4-3/4 in.

(121 mm)

120

2-39/64 in.

(66 mm)

radius

1/4 in.
(6 mm)
diameter
3 holes

120

4-3/4 in.

(121 mm)

4-1/4 in.

(108 mm)

4 in.

(102 mm)

5-1/2 in.

(140 mm)

Transmitter Input
terminal block

12/24
NEG

TP1

L

L

MDM45

Back view

12/24 VDC

=LOAD

L

TP2

4-20 mA
Signal

NC

12/24
NEG

TP1

L

L

MDM45

Back view

12/24 VDC

=LOAD

L

TP2

4-20 mA
Signal

NC

Transmitter Input
terminal block

®

FRANK W.

MFR.

Mounting Hole

Dimensions

Open Transmitter Input

An open transmitter input causes the SWICHGAGE®to
go negative, triggering the low trip point if the trip point
is being used.

Typical Wiring Diagrams

Common Transmitter Power Source

NOTE: Loads must

not exceed 0.5 AMP
@ 250 VDC.
All grounds (-) must
be common.

Separate Transmitter Power Source

How to Order

To order specify trip point output and unit of measure­ment. Example MDM45-B.

MDM45 - ___

Low contact High contact

(decreasing value) (increasing value)

A

* closes closes

B

opens closes

C

closes opens

D

opens opens

*Standard configuration

Note: The MDM45 is for use with Electromechanical TATTLETALE®annunciators or

SELECTRONIC®or similar solid state annunciators.

Warranty

A two year limited warranty on materials and workmanship
is given with this Murphy product. Details are available on
request and are packed with each unit.

In order to consistently bring you the highest quality, full featured products, we reserve the right to change our specifications and designs at any time.

Since 1939

■ Frank W. Murphy Manufacturer

P.O. Box 470248; Tulsa, Oklahoma 74147; USA

tel. [phone] fax [phone]
e-mail [e-mail]

■ Frank W. Murphy Southern Division

P.O. Box 1819; Rosenberg, Texas 77471; USA

tel. [phone] fax [phone]
e-mail [e-mail]

Printed in U.S.A.

■ Frank W. Murphy, Ltd.

Church Rd.; Laverstock, Salisbury SP1 1QZ; U.K.

tel. [phone] fax [phone] tlx 477088
e-mail [e-mail]

■ Frank W. Murphy Pte., Ltd.

No. 2 Tuas South Street 2, Sprintecs Bldg., #02-01/02
Singapore 638042

tel. [phone] fax [phone]
e-mail [e-mail]

■ Murphek Pty., Ltd.

1620 Hume Highway; Campbellfield, Vic 3061; Australia

tel. [phone] fax [phone]
e-mail [e-mail]

NOTE: Loads must
not exceed 0.5 AMP
@ 250 VDC.
All grounds (-) must
be common.

MDM45 Interface Capabilities

Model Power Source Rating

LCDT CD Ign., 120 VAC, 12/24 VDC Cl.I, Div.1, Gr.D, Haz. areas
S1400 120 VAC or 12/24 VDC Cl.I, Div.1, Gr.D, Haz. areas

MARK II CD Ignition, pos. or neg. grnd Cl.I, Div.2, Gr.D, Haz. areas
TATTLETALE
PLC’s, various non-Murphy annunciators–contact factory.

*

An isolation barrier is needed between the MDM45 and an Annunciator rated for
Class I, Division 1, Group D, Hazardous Areas.

**

When used with approved ignition. Contact Murphy for details.

®

CD Ign., 120 VAC, 12/24 VDC Non-Hazardous areas

■ Murphy de México, S.A. de C.V.

Blvd. Antonio Rocha Cordero 300, Fracción del Aguaje
San Luis Potosí, S.L.P.; México 78384

tel. [phone] fax [phone]
e-mail [e-mail]

■ Murphy Switch of California

P.O. Box 900788; Palmdale, California 93590; USA

tel. [phone] fax [phone]
e-mail [e-mail]

■ Frank W. Murphy France

tel. [phone] fax [phone]

0791156

*
*

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