Johnson Controls System 450 Modular Electronic Control

Overview

The Johnson Controls System 450 is a family of compact, modular, digital electronic controls sold under the Johnson Controls PENN brand. Control modules, expansion modules and a power module plug together side by side to build a controller for temperature, pressure and humidity, using on/off relay outputs, proportional analog outputs or both. Johnson Controls positions the System 450 as the next generation of its System 350 and System 27 modular controls, offering more features with fewer than 20 model variations, compared with 54 models in System 350 and 40 in System 27. It is used in HVAC, refrigeration, commercial and industrial process applications wherever a reliable, field-configurable stand-alone controller is preferred to a programmable controller.

Seven Star LLC supplies the Johnson Controls System 450 to HVAC and refrigeration contractors, OEM equipment builders and plant maintenance teams across Oman and the GCC. Our Muscat engineers help select the control module, expansion modules, power module and sensors for each application, and they can map an existing System 350 installation to the equivalent System 450 assembly.

Operating Principle

Each Johnson Controls System 450 assembly is built around a single C450 control module with a backlit LCD and four-button touchpad. The module reads up to three hard-wired inputs, such as A99 PTC temperature sensors, TE-6000 nickel temperature elements, ratiometric pressure transducers, static pressure transducers or humidity transmitters. For every output, the user sets a setpoint, a differential or end point and the sensor that output follows. Relay outputs switch on and off around the setpoint with configurable on and off delays, while analog outputs generate a proportional signal between the setpoint and end point, direct or reverse acting.

Beyond simple proportional action, the Johnson Controls System 450 offers proportional plus integral control with six integration constants, which removes offset error under large constant loads. Multistage control lets several outputs stage equipment such as compressors or fans. High input signal select follows the highest of several sensed values, and differential control maintains a difference between two sensor points. Reset control modules add setpoint reset from an outdoor sensor, real-time setback scheduling and equal run-time balancing, while the C450CPW-400 hybrid module drives variable speed EC motors on condenser fans.

Engineering Design of the Johnson Controls System 450

All Johnson Controls System 450 modules share a compact grey LEXAN housing with DIN rail clips and slotted holes for direct wall mounting. Six-pin connectors on the sides link the modules, which removes field wiring between modules and makes it easy to extend a system later. The C450YNN-1 power module transforms 120/240 VAC to 24 VAC for the assembly; alternatively the modules accept an external 24 VAC Class 2 or SELV supply, but never both at once. A typical standard control module measures 127 by 61 by 61 mm and weighs about 0.2 kg.

Johnson Controls System 450 analog outputs are self-selecting: once connected, each output detects the input of the controlled device and generates either 0 to 10 VDC or 4 to 20 mA. Relay outputs are SPDT dry contacts rated, for the C450CBN-4 and C450CCN-4 modules, at 1/2 HP at 120/240 VAC, 10 A non-inductive at 24/240 VAC and 125 VA pilot duty. Modules are cULus Listed to UL 60730-1, CE compliant and can display Fahrenheit, Celsius, psi, bar, inches of water column and relative humidity.

Key Features

The product bulletin lists these Johnson Controls System 450 features.

• Plug-together modular design with DIN rail or direct wall mounting and no field wiring between modules.
• Field-configurable control modules that can control temperature, pressure and humidity simultaneously.
• Up to three sensor inputs and up to 10 relay or analog outputs in any combination per control system.
• Self-selecting analog outputs of 0 to 10 VDC or 4 to 20 mA, direct or reverse acting.
• Proportional plus integral control, multistage control, differential control and high input signal select.
• Reset control modules with setpoint reset, setback scheduling and equal run-time balancing.
• Communications control modules for RS485 Modbus RTU (C450CRN-1) and Ethernet with integral web server (C450CEN-1).
• Operating ambient of minus 40 to 66 degrees Celsius with 0 to 10 VDC outputs, and up to 95 percent RH non-condensing.

Industrial Applications

In the Gulf climate, condensing units, chillers and cooling towers run hard for most of the year, and simple robust controls are valued. The Johnson Controls System 450 is used for condenser fan cycling and speed control, compressor staging on refrigeration racks in cold stores and supermarkets, boiler and hot water reset in hotels and hospitals, humidity control in archives and clean storage, and pressure control on pumps and air compressors. Its Modbus and Ethernet options let these stand-alone controls report to a building management system in Muscat towers or to a plant SCADA in the Sohar and Salalah industrial areas.

OEM builders of packaged equipment also specify the Johnson Controls System 450 because one small set of models covers many configurations, which simplifies stock. Seven Star LLC supplies Johnson Controls System 450 modules, sensors and transducers, and our Muscat team helps engineers in Oman and the GCC select the right combination and plan replacements for System 350 controls.

Technical Specifications

The table summarises typical Johnson Controls System 450 data from product bulletin LIT-12011458. Values vary by module; see the attached bulletin for each model.

How to Order

To request a quotation for the Johnson Controls System 450, send Seven Star LLC the module part numbers, or describe the inputs, outputs and communications you need. Our Muscat instrumentation division confirms availability, provides the Johnson Controls bulletin for your records and supports engineers in Oman and the GCC with configuration. Related products include the Belimo LF24-SR spring-return damper actuator, the Rittal Blue e+ enclosure cooling units and the Rosemount 2051 pressure transmitter.