TRICOR Systems Inc.
Copyright © 2001 TRICOR Systems Inc. All Rights Reserved. Printed in the United States of America No part of this publication may be reproduced in any form by any means without the express written permission of TRICOR Systems Inc. The information in this document is subject to change without notice. TRICOR Systems Inc. makes no representations or warranties with respect to the contents of this manual and specifically disclaims any implied warranties of fitness for a particular purpose. TRICOR Systems Inc.
Contents Section Page 1 Introduction ......................................................................................................... 4 2 Getting Started .................................................................................................... 6 3 Testing ............................................................................................................... 11 4 Configuration ................................................................................................
Section 1 Introduction Tester Description The Model 933A Life Cycle Test System (LCTS) is a complete and ready to use piece of test equipment for the endurance testing of materials and electrical switches. The LCTS can be configured to continuously depress a test sample using a pneumatically controlled cylinder. The Model 933A is designed to measure one electrical contact with each up/down stroke according to ASTM Designation F1578 - 96.
The application software can configure all the programmable features of the LCTS including test times, resistance and bounce tolerances and maximum event counts. It has a “learn” mode for switches to automatically set test tolerances and a mode for manual operation and contact measurement. The software can be set up to store the test results to an open file. The file format is comma delimited text which is easily imported to other programs such as Microsoft Excel and Access.
Section 2 Getting Started General This section is for new users and describes the installation and hookup of the Life Cycle Test System. The user supplied resources are discussed and verification of proper setup is provided. User Supplied Resources The LCTS uses shop air to drive the pneumatic air cylinder. There is a coupling on the back of the Controller Unit which will accept a standard 1/4 inch NPT quick disconnect hose coupling. The user must supply the air using a sleeve lock socket.
Software Installation Begin the setup process by installing the application software. This software is on the CD provided with the basic unit. Since you are viewing the manual provided on this disk it is assumed that the installation should be complete. If not, follow the instructions below. • Close all other windows applications before starting the installation. • Insert the 933A Software installation CD in the CD disk drive of your computer.
Air Cylinder Coupling Test Contacts Terminal Connection Air Inlet Coupling Expansion Connector Serial Data Connector Power Connector Figure 1. Back of Control Unit Equipment Setup Connect a supply of air to the air inlet coupling on the back of the Control Unit (Figure 1). This fitting accepts a 1/4 NPT quick disconnect sleeve lock socket. The Test Head is delivered mounted on the slide post.
Figure 2. Slide Post Mounted to Base Plate Force Adjustment Pressure Gauge Status Indicators Control Switches Figure 3.
with a test configuration that will cycle the air cylinder 10 times per second. Press the Start button on the Control Unit to cycle the cylinder. Press Stop when satisfied that the setup is functional. To configure the LCTS to test your specific device, it must be connected to the personal computer (PC) running the software application provided. Attach the 9-pin adaptor to either end of the 20 foot serial cable with modular connectors (both provided).
Section 3 Testing Test Methods The LCTS uses a single chip microprocessor for control and test measurement. Integrated into the design is nonvolatile data storage. This allows the unit to be stopped and powered down without losing the configuration information or accumulated test data. The LCTS does not retain test results for each test cycle. Instead, it keeps a running value for the minimum and maximum contact value measured.
to the constant transfer interruption. Also, the amount of data gathered will quickly become unmanageable. The LCTS is a life cycle tester and is not intended for continuous data collection. Test Circuitry A simplified diagram of the contact measurement circuitry is shown in figure 6. The contact is measured using a precision 1.00 KOhm pullup resistor to a 5 volt power source. The switch contact is arranged between this resistor and ground.
directly affect the results of bounce testing. The maximum air pressure used to actuate the air cylinder and the adjustment of the air flow restrictors (optional and not part of the basic LCTS) will affect bounce measurements as well as overall test speed. Consider these variables when making bounce measurements. Slower test speed results in longer bounce values. Figure 7 illustrates the voltage measured across a typical normally open contact as it is actuated. The open circuit voltage is 5.
value measured must be above the SUTV. For the closed condition, the measured value must be below the SLTV threshold. It is important to set these threshold values even if bounce testing is not performed. If improperly set, the switch may fail the initial state condition test. This test is performed whenever contact resistance testing is performed. Bounce testing can only be performed if contact resistance testing is performed. It makes no sense to test bounce if final contact resistance is not proper.
continues until the elastomer tip on the cylinder reaches the switch. The tip and the switch now begin to deform until the electrical contact first closes. When the measured contact resistance falls below the SLTV for the first time, a free running counter is read to record this initial event. Each time, including the first time that the measured contact value transitions through SUTV and then SLTV, the counter is latched.
three of these counters can be individually reset under user control from the software application. The red failure LED on the front panel of the Controller Unit will illuminate if the individual cycle fails. It will be extinguished if all the tests of that cycle pass. The LED will be pulsing if the switch is randomly failing. The 4 failure conditions of each half cycle may not all be active. The following table shows the possible variations. The up and down strokes are independently set.
Cylinder Maximum Down Time Contact Minimum Down Time Reduced Time Figure 9. Testing Speed-Up Without knowledge of the contact closure, the user is forced to configure the LCTS so that the Maximum Test Time has enough padding to allow for variations in the plunger travel time to get to the switch, the switch travel time, the bounce and stabilize times of the switch as well as the variations that may result from temperature and pressure uncertainties.
Section 4 Configuration LCTS Configuration The main window of the LCTS software application is shown in Figure 10. The recessed areas and check boxes show test results gathered from the LCTS. The data in nonrecessed areas indicated test parameters and configuration settings used in verification of the tested item. This window shows all the test result data downloaded from the LCTS. It shows most, but not all, of the configuration parameters.
How to Configure the LCTS The LCTS was designed to test keypads and switches. These devices have an electrical contact. The resistance of this contact is part of the test measurement, and pass/fail criteria is assigned to the results obtained. To learn how to configure the LCTS for an electrical switch see the section below on Configuring For Devices With Contacts. The LCTS can also be used to test devices that don’t have an electrical contact. In this case, there is no test data collected on the item.
Figure 11. Model 933A Application Software Configuration Dialog, Test Time Tab Configuring For Devices Without Contacts Edit the current configuration parameters by opening the configuration dialog. See Editing The Configuration, above, for details. Select the Contacts tab at the top of the dialog. Be sure the Contact Type is set to “None” (Figure 12). This will disable all contact testing. Choose the Test Time tab. Set the maximum up and down times based on the test criteria.
Figure 12. Model 933A Application Software Configuration Dialog, Contacts Tab Figure 13.
Configuring For Devices With Contacts Edit the current configuration parameters by opening the configuration dialog. See Editing The Configuration, above, for details. Select the Contacts tab at the top of the dialog. Set the Contact Type to the type of switch to be tested, Normally Open (NO) or Normally Closed (NC) (Figure 11). This will establish the state of the contact when the air cylinder is in the up (retracted) position.
Choose the Limits tab on the configuration dialog. These limits are events which will stop the testing. Exceeding any of these limits will halt the LCTS. The range for all limits is between 1 and 10,000,000 events. Set the Test Cycles limit to the number of tests to perform on the switch item. Since this device has a contact which is being tested, there is a pass/fail status for each test cycle. The total number of failures and the number of sequential failures is counted.
Choose the Learn menu item under the Configuration menu. The dialog shown in Figure 15 is displayed. The user must tell the system the type of switch contact (NO/NC) and whether bounce will be tested. With the switch attached and in its fixture, press the OK button. A relatively slow test of the switch is repeated 10 times until a cumulative average is obtained. These test results are downloaded and used to calculate the configuration parameters. The configuration data dialog box is then displayed.
Section 5 Test Results Test Data The application software gathers the cumulative test data from the LCTS every time it first connects to the LCTS, every time the LCTS is stopped (by whatever means) and when the Sample button is pressed. All data downloaded is displayed in the main window screen. The current test data can be printed by selecting the Print menu item under the File menu. The contents of the printed page depends on what items of the device are tested.
When the break update run mode is selected, the user is caution to enter a relatively large value. The LCTS is a life cycle tester. It is not intended to take data readings with every test cycle. Windows has unpredictable timing. Setting the update count less than 20 usually get the LCTS and software application into a race condition which eventually locks out the communications. Close and restart the application to restore communications. Use an update count greater than 100.
Section 6 Force and Speed Life Cycle Testing The LCTS was designed for life cycle testing. It will exercise the test sample through to final wear out. It normally takes millions of test cycles to reach the wear out point. For this reason, it is important to reduce the time of each test cycle. The total test program will then be completed in a minimum amount of time. Reduce Mechanical Stroke Time The first, and most effective, method of increasing the cycle rate is to decrease the mechanical stroke times.
