Myron L CTCIITD - Manual (Page 19)

III. OPTIONS &
ACCESSORIES
A. LIMIT TIMER MODULE OPTION
LTMO Limit Timer Module Kit ordered separately.
1. DESCRIPTION
This module allows the user to set a “limit” of up to 120 minutes
on the length of time the feed pump will operate.
Specifications:
Control Function:
Controls the Feed Pump Relay only.
2. INSTALLATION
Briefly -
The Limit Timer Module simply plugs into the CTCII circuit board,
see figure III.B.4.
WARNING: BEFORE STARTING, IF MONITOR/CONTROLLER
IS INSTALLED, ENSURE THE POWER IS OFF. FAILURE TO
DO SO COULD CAUSE DAMAGE TO THE INSTRUMENT, AND
COULD BE HARMFUL OR FATAL TO PERSONNEL. ONLY
QUALIFIED PERSONNEL SHOULD INSTALL OR SERVICE
ELECTRICAL EQUIPMENT.
Physical
NOTE: When opening instrument, remove front panel with care. If
the front panel has already been removed from the enclosure skip
to #3.
1. Using a Phillips Head screwdriver remove the four (4)
screws on the clear cover.
2. Remove clear cover.
3. The front panel is held in place with hook & loop strips
on each side. By carefully lifting at the slot on the top,
the front panel will pull toward you. Do not pull more than
about 8 inches/20CM.
DO NOT pull on control knob(s).
4. Rotate the front panel down so that the back side is
facing you. The Circuit Board is mounted to the back of
the front panel.
5. Carefully press the LT Limit Timer Module into the Circuit
Board as shown in figure III.A.4.
When fully seated the LTMO option will snap into place.
6. Reassemble front panel.
7. Turn shaft fully counter-clockwise.
8. Install knob on shaft and align to “DOT”.
9. Reinstall clear cover.
B. C4A MODULE
(4-20 mA OPTION)
-C4A 4-20 mA Self/Remote-powered Isolated output module
ordered with controller.
C4AO 4-20 mA Self/Remote-powered Isolated output module
ordered separately.
1. DESCRIPTION
The 4-20 mA option gives the CTCII controller the ability to
send a signal very long distances with minimal interferences and
signal degradation. The output is an Isolated 4-20 mA signal that
corresponds to the full scale range of the controller into which it is
installed. This output is easily configured to be either self-powered
or remote-powered as required for your particular application.
NOTE: The maximum impedance of the user’s current input
instrument should not exceed 600 ohms.
Since the output is an isolated current loop, it is the ideal choice
for applications requiring; a control signal to be run very long
distances, systems requiring a 4-20mA input or in instances where
isolation is necessary.
As the output is isolated, and a current, it is useful for long
distance interface, especially where wiring resistances may be
high, and/or the ground potentials may differ between the sensor
input ground and the current receiving instruments ground.
The 4-20 mA output will not be degraded in accuracy even
when the ground differences are as much as 120 VAC @ 60Hz.
Interface wire resistance of 350Ω will not degrade the accuracy of
the output when interfaced to a typical 250Ω input impedance of a
transmitter current input device.
The output is capable of driving a minimum of 600Ω worse case,
therefore, will satisfy virtually all modern interface requirements.
Current input devices usually have an input impedance of 250Ω,
however, some older designs can have as high as 500Ω or as
low as 10Ω. This “-C4A” option will drive any impedance from 0 to
600Ω without any degradation of performance.
There are two modes in which current loop transmitters operate;
Self-Powered and Remote-Powered.
Self-Powered — the transmitter provides the power to drive
the 4 to 20 mA current. See figure III.B.1.
Remote-powered — the receiving instrument provides the
power to drive the 4 to 20 mA current. See figure III.B.2.
Figure III.A.1
! CAUTION - READ FOLLOWING CAREFULLY
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