Introduction; Overview - Honeywell UDC2300 Product Manual

1.1 Overview

Introduction

UDC2300 Limit Controllers accept input signals from any of several types of external
sensors such as Thermocouples (T/Cs) and Resistance Temperature Detectors (RTDs). It
conditions these signals, as necessary, to derive the equivalent Process Variable (PV)
value that drives various circuits in the controller.
The equivalent PV signal is compared with the Limit control set point and any error
signal from the differential amplifier de-energizes the coil of an electromechanical,
single-pole, single-throw (SPST) limit output relay.
When de-energized, the output relay "Locks Out" and remains that way until the PV input
signal drops below the High Limit Set Point or goes above the Low Limit Set Point and
the controller is reset manually via the keyboard or from a remote location (Contact Input
Option).
You can select normally open (N.O.) or normally closed (N.C.) Limit Relay Contacts
simply by moving a jumper.
The contact of the output relay terminates at the rear terminal of the controller to which
you make the appropriate field wiring connections.
A flashing "LIMIT" in the lower display indicates that the output relay is de-energized.
High Limit Controller
When the PV input signal is below the limit set point, the output relay energizes. If the
PV signal exceeds the limit set point, the output relay de-energizes and the flashing
"LIMIT" display is turned on.
When the PV signal returns to a value below the limit set point, the controller can be reset
manually using the MAN-AUTO RESET key or Contact Input Option.
Low Limit Controller
When the PV input signal is above the limit set point, the output relay energizes. If the
PV signal falls below the limit set point, the output relay de-energizes and the flashing
"LIMIT" display is turned on.
When the PV signal returns to a value above the limit set point, the controller can be reset
manually using the MAN-AUTO RESET key or Contact Input Option.
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1 Introduction
UDC2300 Limit Controller Product Manual
Introduction
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