Distributed Manufacturing Test System for Vacuum Tubes Using Programmable Automation Controllers and Modular Instruments

Author(s):
Lakshmana S. Kumar - Apna Technologies & Solutions
Ceri Baskar - Apna Technologies & Solutions

Industry:
Manufacturing

Products:
FieldPoint, PXI/CompactPCI, LabVIEW

The Challenge:
Testing custom passive vacuum tubes across nine distributed individual test stations and sending the test results and data to a centralized database server for analysis and future storage.

The Solution:
Implementing a flexible, user-friendly, and distributed test system developed using National Instruments programmable automation controllers (PACs), modular instruments, and data acquisition devices in conjunction with NI LabVIEW software and the LabVIEW Real-Time Module.

Bharat Electronics, Ltd (BEL) is an electronics manufacturer that produces electronic and telecommunications equipment. The Passive Vacuum Devices Division at BEL has manufactured Vacuum Interrupter (V.I.) tubes since 1985 and has continually sought improvement on tube testing, data collection and analysis, and corrective and preventive action by automating the process. Current testing processes are manual, and this project was envisaged to automate the tests distributed at nine stations by integrating the existing testing equipment with appropriate data acquisition and application software.

 

The distributed test system was developed using LabVIEW and involves data logging and analysis from nine distributed acquisition stations, five of which PAC stations are independent real-time NI FieldPoint acquisition stations, and two are PC-based data acquisition stations with modular instruments. At each station the unit under test (UUT) is tracked by barcode, and the test parameters are logged and updated to the server database where each test is consolidated based on the stem number.

System Requirements

The system had several basic requirements:

• Interfacing with the current test equipment
• Performing accurate testing on the individual stations distributed on the manufacturing floor
• Acquiring test parameters and analyzing the data of each station
• Controlling the working operation of each station through a centralized server
• Consolidating all station test parameters based on stem numbers on the centralized server
• Producing reports based on user requirements
• Updating data on the server by a “one-click” option
• Monitoring production in a centralized manner

 

System Description

Four types of tests are conducted on each V.I., including:

• Contact resistance (CR) – one station
• Aging test – five stations – aging MWB1, MWB2, MWB4, MWB3, JRC
• Impulse test – two stations –impulse MWB3, JRC
• Vacuum test – one station

 

Each V.I. is scanned for the barcode at every station before the testing process and goes through all four tests in the stations based on the V.I. type.

 

Contact Resistance Station

The CR station is a data acquisition station using FieldPoint that determines the resistance of the vacuum tubes by measuring the voltage. Each tube is identified by the stem number, which is in the barcode format. The obtained voltage is converted into resistance by measuring currents up to 100 A. The user initiates data logging by pressing the button on the panel. The contact resistance should be within specified limits for each V.I. to limit the heating of V.I. tubes through ohmic current heat loss.

 

AC Aging and Power Frequency Withstand Test (PFWT)

AC aging is based on both PC and FieldPoint data acquisition stations that determine the voltage and current of the vacuum tube. Three types of tests are conducted: chamber aging, contact aging, and PFWT. The voltage and current obtained from the test station is very high and appropriate LEM current and voltage sensors are used before interfacing with the FieldPoint and data acquisition hardware. The tube name and type is set based on the PFWT voltage comparison with the voltage limits on the setup file.

 

Impulse Test

The impulse test system is based on an NI PCI-5112 that captures the impulse waveform of the tube under test. The system captures both positive and negative impulse waveforms and the captured waveforms are analyzed and stored.

 

Vacuum Test

Measurement of vacuum by ionization current method at various stages of the test process ensures the vacuum integrity of the V.I. tube.

 

Server

The data from individual stations that are stored as files are collected at the centralized point based on the user configuration. The communication between clients and server is through TCP/IP and file transfer that happens through FTP. The server also performs other operations,  including setup entry, individual station file view, manual data entry, and report generation.

 

Application Software and Modules

The application software was developed in LabVIEW and LabVIEW Real-Time for PAC. The client and server run different application modules.

 

Test Station Application Modules

Authentication module – This module checks for the authorized user entry and gives user-wise features

 

Barcode module – This module takes the reading from the barcode and is used before starting the test at each station

 

Data acquisition module – Each test station has its own data acquisition module and logging system

 

User interface module – Each PC-based acquisition system has an interface to start the acquisition, control the process, and measure the required parameters

 

Communication module – This module establishes and maintains the communication between clients (both FieldPoint and PC) and the server

 

File transfer module – This module transfers the individual files from the clients to the server based on user instructions

 

Server Station Application Modules

Communication module – This module establishes and maintains the communication between clients (both FiledPoint and PC) and the server

 

Setup module – With this centralized user interface module, users configure the test parameters according to the test needs. All test station parameters are entered under one tube type and saved for the future. The configured parameters for each test and tube type will be uploaded to the individual stations using TCP/IP and FTP communication.

 

Client station view module – Data that are transferred from each individual station can be viewed on the server

 

Manual data entry module – Manual data entry gives the user the option of entering an individual station’s data, or the measured parameters of the tube under test can be manually updated to the server through this option. Only administrator and super users can access this option.

 

Report Module - Data collected from all the stations are consolidated in the server. Reports are generated based on stem number, date, tube type or name, or PFWT voltage. The saved reports can also be previewed before printing. All the reports are generated using the LabVIEW Report Generation Toolkit and are saved in an Excel format.

 

The fact that National Instruments hardware works so easily in a networked environment and integrates well with networked application software created in LabVIEW was a huge advantage while developing this distributed test system. Using LabVIEW, LabVIEW Real-Time, and the NI data acquisition platform, we implemented a high-performance, flexible, and distributed test system that was otherwise fully manual.

 

For more information, contact:

 

 Ceri Baskar

 

Apna Technologies & Solutions

 

No.1 Coconut Garden, Out Rind Road, Kalyan Nagar P.O

 

Banaswadi, Bangalore, India - 43

 

Tel: 080-25426463

 

Fax: 080- 25426518

 

E-mail: baskar.ceri@apnatech.com

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