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LCDT-8535B page 1 of 2

Description 

The LCDT Selectronic Tattletale system is a compact fault
annunciator with an electronic alarm/shutdown control system. It was
designed to protect engine-driven or motor-driven compressors
and pumps. The annunciator indicates the sensor, and hence the
parameter, that causes an alarm or shutdown. In addition, a
means is provided for testing the operation of each sensor without
initiating an alarm or shutdown. Employing a liquid crystal display,
the LCDT system gives a digital reading of the tripped sensor and
the lockout timer countdown. 

As the heart of the system, the basic annunciator component has
two variations: the Model LCDT-NO, which accommodates normally
open sensors, and the Model LCDT-NC, which accommodates
normally closed sensors. These units are enclosed in an aluminum
box having a brush finish. The LCDT system accommodates 47
sensor inputs, 15 of which may be locked out during start-up by the
start/run timer delay.

A separate power supply is provided with the model LCDT
instrument. Power may be supplied by CD ignition, a 120 VAC
line, or by 12 or 24 VDC battery.

Intended for use with all Swichgage instruments without 
“OS” option.

Features 

System alarm or shutdown for up to 47 sensors.

Timed start-up overrride for up to 15 sensors.

Liquid Crystal Display of tripped sensors and the lockout timer
countdown.

Test timer for shutdown override during sensor test.

Intrinsically safe annunciator unit; Class 

I

, Division 1, Group D

Hazardous Locations.

Explosion-proof power supply.

A battery maintains the electronics while the engine is 

not running.

Optional 3-second time delay allows a fuel valve to close

before grounding the ignition.

Specifications

Power: 

Supplied by CD ignition of an engine, 120 VAC line, or

by 12 or 24 VDC battery.  

Power Inputs (Operating Voltage):

LCDT-PS-CD (R)-P: 

90-250 VDC, CD ignition, positive ground.

LCDT-PS-CD-N: 

90-250 VDC CD ignition, negative ground. 

LCDT-PS-120/24/12: 

120 VAC (6 VA), 24 VDC (1 watt),

12 VDC (0.5 watts). 

Sensor Inputs:

Accepts up to 47 sensors (NC version only 45) via

a ribbon cable. The LCDT system was designed to be used with
sensor switches having  normally open or normally closed
contacts such as Murphy Swichgage instrument. 

NOTE:

An

approved isolation barrier such as a thermocouple type barrier,
must be used between sensor switch and input terminals if sensor
outputs come from any energy storing device such as a relay or
transistor.

Relay Outputs Ratings:

LCDT-PS-CD (R)-P Contact rating: 

4A, 

1

/

20

HP, 

125/250 VAC/3A, 30 VDC.

LCDT-PS-120/24/12 Contact Rating: 

5A, 28 VDC. 

120 VAC (resistive).

FET Outputs:

LCDT-PS-CD-N rating (for fuel valve and 

ignition ground): 

0.5A @ 250 V.

Alarm Relay Contact Rating:

4A, 

1

/

20

HP, 125/250 VAC/3A, 30 VDC.

Operating Temperature: 

Module (head): 

-40 to 185°F (-40 to 85°C).

Power Supply: 

0 to 158°F (-18 to 70°C)

Storage Temperature: 

-40 to 302°F (-40 to 150°C). 

Case: 

LCDT-NO/NC (module): 

anodized aluminum.

Power Supply (all models): 

Explosion-proof aluminum.

Multiplexer Scan Rate:

Scans all 47 sensors in 0.7 sec.

Start-Run/Test Timer:

Standard 5 minutes, specify other, up to

7 minutes maximum (in 1 minute increments).

Laboratory Approvals:

CSA

*

and Factory Mutual System

**

Listed

for Class 

I

, Division 1, Group D, Hazardous Locations.

*

When used with approved ignitionA. Contact Murphy for details.

* *

When installed per Murphy drawings HC-9450-A (50-08-0021) or HC-9450-AA

(50-08-0019).

Monitor Engine or 
Motor Driven Pumps 
and Compressors

47 Normally Open (N.O.)
or Normally Closed 
(N.C.) Sensor Inputs

CSA

*

and Factory 

Mutual

**

Listed

Rated for Hazardous 
Locations

LCDT-8535B

Revised 07-06

Catalog Section 50

LCDT Selectronic

®

Tattletale

®

System

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