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3.0 OPTIONS
The standard Model 1250-LTC is configured with three options – Analog Output,
Hi/Lo Relays, and a Serial Port (RS-232 or RS-485). One more option is available – Input
Isolation. This section describes general use of each option, including wiring and
programming for each option.
3.1 Analog Output Option “-0”, “-1”, “-2”, “-4”
The analog output on the 1250-LTC may be used to feed position information to an
LTC Controller, a remote monitoring system such as SCADA, RTU or a remote indicator
such as the INCON model 1511-Z. In the all modes, the analog output automatically spans
between the highest and lowest taps.
Wiring:
The 4-20mA analog output option must be wired with an external power supply of
15.0 to 24.0 volts DC in series with the analog output current loop. (See Figure 1.3, page 7)
The INCON Model 1945 is available for this purpose. All other analog output options are
self-powered. Refer to Table 3.1 below for analog output load limits.
Table 3.1 Analog Output Load Limits
Analog Output: Load Minimum Load Maximum
0 to 1 mA Zero Ohms 10K Ohms
+/- 1 mA Zero Ohms 10K Ohms
0 to 2 mA Zero Ohms 5K Ohms
4-20 mA Zero Ohms 500 Ohms
Note:
If the presence of high voltage AC “ripple” is found on the analog output terminals, it
is generally not a problem with the 1250-LTC itself. Check the isolation of all field wiring
with respect to earth ground. All wiring should be completely isolated from ground. See
Section 3.5, page 48 Input Isolation Option. Contact INCON Technical Service for assistance
if the problem persists.
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