Beverage refrigeration system testing with MW100

Introduction

A major soft drink manufacturer dictates strict quality control standards to companies that manufacture vending machines, coolers, and dispensing equipment that handle the branded products of the company.

The company operates an engineering lab at corporate headquarters in Atlanta where numerous environmental rooms can simulate any climate condition where a vending machine or cooler may operate. Testing of all types of vending machine and dispensing equipment is conducted in these environmental rooms.

Application

An environmental room consists of four or five test stations. Each station includes a relay control for starting/stopping the unit under test, an AC power meter to measure load, and a patch panel of 40-50 type T thermocouples. Room temperature and humidity are also measured. All thermocouples and control cabling leave the room and are bundled into the adjacent lab area where they are wired to a National Instruments SCXI data acquisition system. LabVIEW software handles monitoring and multiple mode logging to the PC for each test cycle.

A test cycle consists of loading the unit under test with product cans or bottles filled with glycol and a thermocouple probe. The system is then "soaked" for a time period to reach the ambient temperature of the room. The room can simulate any temperature/humidity combination- from Miami Beach in the summer, to a Montana winter. The test begins by switching on the cooling system. Temperature data from all product containers as well as the electrical load of the cooling system is monitored for the test duration. The completed test data file is converted to Excel format for analysis and formatting into a corporate report. The objective of the test is to ensure that the unit under test has the capacity to draw down the product temperature within a prescribed time period, and cool the product uniformly and adequately over the expected range of environmental conditions.

The customer began looking for a replacement data acquisition system, with the primary objective of replacing LabVIEW with an off-the-shelf software solution that provided equal or better functionality but without the need for custom integration work. The original LabVIEW application never fully met expectations because of problems with the integration firm that designed the application.

A new hardware platform that is Ethernet based with higher measurement quality, new convenience functions and backup data logging were also new system criteria.

The new system must be a functional replacement for the original system. Of most importance, the software must allow the operator to start and stop a test for each station independently. The system must also activate a load relay that energizes the cooling system under test at the beginning of the test cycle.

Solution

The local Yokogawa Test and Measurement sales rep that has an established relationship with the customer was contacted to discuss the new project.

A meeting was scheduled and the project details were defined. The MW100 was recommended as the data acquisition platform, including the DAQWORX software suite with AddMulti, and the PR300 power meter.

Four MW100 systems and four PR300s were purchased for the first environmental room. Approximately 220 thermocouple inputs from the four stations are wired to the four systems. One MW100 includes a 10-channel alarm relay output module and is assigned to switch the load relays for the units under test at each station. This MW100 is also assigned the task of reading the PR300 power parameters via the MODBUS client function.

The customer inquired about a "turn key" installation that included assembly of the MW100 components to a panel and mounting the panel to the wall in the lab. In addition, all of the signal wiring had to be transferred from the old NI system to the MW100 and then dressed and labeled. The sales rep was able to quote this work through a local Yokogawa systems integration firm and this was included with the customer's order.

The completed panel was delivered and installed over the Christmas holiday, in time to commence start up when the customer returned to work after New Year's.

All four MW100s and PR300 power meters are placed on the corporate network along with the lab PC. The customer uses a web browser to configure each MW100 and for manual start/stop control of each test station's cooling system under test. DAQWORX GateMXMW, DAQLOGGER, and AddMulti software components handle the data communication, trending and display, and multi-interval reporting functions, respectively. This all- Yokogawa software package provides a sub- $1k solution that required no integration services.

The system benefits include:

• On-board data storage that can back up test data in the event of PC or network failure.
• Ability to interface to the PR300 Power Meter via MODBUS TCP.
• "Out of the box" low cost software that provided all of the needed data display and multi-interval logging functions.
• File conversion to Excel for reporting
• Turn-key installation by local Yokogawa system integrator.

Additional References:

For detailed product information and specifications, see the following documents:

• MW100 Bulletin; 04M10B01-01E
• MW100 General Specifications; GS04M10B01-01E