Split Package Systems

M&M Systems produces a fully configurable Spit Package Control System (SPCS) which uses distributed methodology to control Heating, Ventilation, Air Conditioning and Refrigeration (HVAC/R) equipment.

The SPCS provides various optional safety controls and monitoring points to improve system performance and reduce energy cost. Control panels may be located close to the controlled equipment to reduce wiring costs. An RS-422 multi-drop serial communications network is used to connect multiple control panels to a Master control panel for alarm reporting, data logging and interface to the PC-based monitoring system.

The system allows any controller to be configured as the Master and consists of the following major components:

  • Mini Controller
  • Sensors
  • PC Interface

General Overview

Controlling the room temperature is the primary function of the SPCS and controlling the evaporator liquid valve is the minimum required control operation. Compressors, condensers and fans may or may not be controllable, depending on how much additional wiring or contractors are added to the equipment. Also included are various optional safety controls and monitoring points to improve system performance and reduce energy cost.

Some of the basic features of the SPCS include:

  • Full Featured, Reliable, Affordable, User Configurable
  • Control For Single Unit With Up To Two Fans/Coils
  • Compressor Monitoring: Running Status & Safeties
  • Extremely Informative Logging System: Records All Sensor Values, Alarms And Failures
  • Centralized HMI Allows Multiple Panels To Be Linked Together
  • NEMA 4X Enclosure: 14”H x 14”W x 4”D
  • Password Protection And Tracking
  • Control Features

The SPCS Mini Controller is housed in a waterproof, corrosion-resistant enclosure designed to NEMA-4 specifications. The design of the SPCS has been built for both outdoor and indoor industrial environments.

Typical Split Package refrigeration systems consist of two primary components, the Condensing Unit and the Evaporator. The SPCS panel may be mounted in any convenient location; such as the rooftop by the condensing unit, within the refrigerated space next to the evaporator in a machinery room or a hallway.

Inside the enclosure is a microprocessor based controller powered by an AC/DC universal input power supply. Connections to the unit are through the bottom of the enclosure and utilize waterproof connectors. The hardware requires no operator intervention in the event of a power failure.

Multiple controllers can be link together via a communications cable to allow the PC based HMI interface to access all units. An interface is also provided for a PC, Laptop or other hand-held device to allow qualified maintenance personnel access to more advanced system functions and for programming purposes. The controller supports an optional local display and keypad to allow for a permanent interface.

The system provides a full complement of software functions to allow each controller to be customized to meet facility requirements. An overview of the major control features provided by the SPCS are as follows:

  • Control Support For Different Types Of Valve Stations & Defrost Methods
  • Liquid, Suction, Pre-Defrost, Defrost, Post-Defrost, Etc.
  • Air Unit Fans May Be Set To Cycle With Temperature For Energy Savings
  • Programmable Fan-On Delays, Fan-Off Delays And Fan Sampling For De-Stratification
  • Override Commands – Cooling, Stop, Max Cool, Defrost, Stop Defrost And Pump-Out & Stop
  • External Shutdown/Standby Input Operates Locally Or Globally From Master Panel
  • Master Panel Provides User Programmable Staging Control For Bringing Units Back On-Line After A Power Failure Based On Temperature And User Defined Priorities To Reduce Demand Spikes And Lower Energy Costs
  • Temperature Scheduling Allows For Peak Load Shifting To Reduce Energy Cost
  • Each Unit Has Four Programmable Setpoint Groups (Cooling/Heating, Deadband, High And Low Alarm Setpoints)
  • Support For Various Types Of Defrost (Hot Gas, Air, Electric, Water, Etc.)
  • Defrost Based On Liquid Feed Runtime, Fixed Time Schedules Or A Demand Defrost Input
  • Support For Multiple Defrost Terminate Inputs. Temperature Sensor or Switch Inputs Supported For One or Two Coils.
  • Defrost Queue Limits The Number Of Units Allowed To Defrost At The Same Time To Reduce Demand Spike And Lower Energy Costs
  • Built-In Support For ModBus RTU Protocol
  • Built-In Communications For Linking Up To 31 Controllers