The Power Supply monitoring function allows you to view, via the Weld Heat display screen, the actual amount of heat delivered during both Weld 1 and Weld 2 for a selected weld schedule.
With this information, you can refine parameter settings as necessary following a weld to optimize the weld parameters.
The monitoring function also oversees operation of the Power Supply. Where errors occur, the display screen presents an error message and the Power Supply outputs an error signal for external equipment to monitor.
Monitoring Weld Heat Limits. Assume that you wish to monitor the weld heat limits for the example weld schedule that you previously programmed in this chapter under
Setting the Weld Schedule. To activate the weld heat monitor (in this case, the current monitor) and set monitor current limits:
1. Press the MODE key to access the Mode Selection display screen.
2. With the CURSOR keys, move the
cursor to the display IM (current monitor) field.
3. With the DATA keys, set the character to 1 (Weld 1 heat monitor ON).
4. Press the MONITOR SET key to access the Monitor Limits display screen.
5. With the CURSOR keys, move the cursor to the display SCHEDULE field.
6. With the DATA keys, enter 1 for Weld Schedule 1.
7. Assume that you have programmed weld current for Weld Schedule 1, Weld 1, at 1.0 KA, and you wish to limit the current positive swing to 1.10 KA and the negative swing to 0.95 KA. With the CURSOR keys, move the cursor to the + current limit field.
8. With the DATA keys, enter 1.10.
9. With the CURSOR keys, move the cursor to the - current limit field.
10. With the DATA keys, enter 0.95. With the example of monitoring with the deviations that you set and 1.0 KA of programmed weld current, limit errors are illustrated as follows:
You turn on the voltage (VM) and power (WM) monitor similarly. In steps 2 and 3, you would set VM = 1 for the voltage monitor or WM = 1 for the power monitor instead of IM = 1. The high and low limit alarm events shown in the preceding illustration result in a TROUBLE signal output at the I/O connector (see Appendix B) and an alarm message on the display screen (see Appendix D) at the end of the weld cycle.
The operational events will depend on the setting that you specify for MR in the Mode Selection display screen. On exceeding an upper or lower current, voltage or power limit, the following will occur depending on the setting for MR (see Appendix B for the I/O connector definition):
MR = 0: An END signal will be output through the I/O connector. The error state can be reset by the next START signal or a TROUBLE RESET signal input at the I/O connector.
MR = 1: No END signal will be output, so the next START signal will not be accepted. The error state can be reset only by a TROUBLE RESET signal at the I/O connector.
Current Setting Monitor (IP-217A Only). The IT-500A Welding Transformer has a maximum current output capability of 2.0 KA. When it is selected, if you program 2.01 KA or greater welding current, a current setting monitor will not allow the system to start. The display screen will display the message CURR SET ERROR !! and the TROUBLE signal will be output at the I/O connector. To remedy the error condition, you must either program a current setting below 2.0 KA or connect a welding transformer with higher current output capability, and apply a TROUBLE RESET signal at the I/O connector.
Monitoring Average Pulse Width. The control pulse activates the welding
transformer after the start of the weld cycle. Its width is a measure of how much time is left in the duty cycle of the welding transformer before it will be damaged by exceeding its rated duty cycle.
You view the average pulse width for Weld 1 and Weld 2 on the Average Pulse Width display screen. For example, an average pulse width of 75% indicates that the transformer is operating with a 25% margin of safety. To access this display, press the MON. 2 key.
If the control pulse average width is 100% for more than 5 milliseconds during the weld cycle,
a TROUBLE signal will be output through the I/O connector. The display screen will display the alarm message FULL WAVE !!. Operation will be restored by the next START signal or
TROUBLE RESET signal input through the I/O connector.
Automatic Performance Monitors. In addition to the previously described performance monitors whose limits you can program, there are several performance monitors which respond automatically to alarm or error conditions without your intervention. These monitors each place an appropriate alarm message on the display screen and output the TROUBLE signal at the I/O connector. Please refer to Appendix E for the alarm messages and operator remedies, and to Appendix B for signal details. The monitors set up special operational states when the following error conditions occur:
Control Limit Monitor: The welding transformer control pulse width goes full wave (100% of the transformer capacity at its duty cycle) for more than 5 milliseconds dur-ing the weld cycle. The weld cycle will be completed. The next START signal will reset the error and start the next weld cycle. A TROUBLE RESET signal input at the I/O connector will also reset the error.
No Current Monitor: With the Constant Current Control mode active, the weld current is less than 25 (50 for the IP-217A) amperes after 5 milliseconds from the start of the weld cycle. Welding stops. A TROUBLE RESET signal at the I/O connector will be needed to reset the error condition and restore welding capability.
No Voltage Monitor: With the Constant Voltage Control or Constant Power Control mode active, voltage is lower than 0.05 volts after 5 milliseconds from the start of the weld cycle. Welding stops. A TROUBLE RESET signal at the I/O connector will be needed to reset the error condition and restore welding capability.
Transformer Thermostat Monitor: The welding transformer has overheated. The transformer thermostat has been tripped and welding is off. A TROUBLE RESET signal at the I/O connector will be needed to reset the error condition and restore welding capability.
Excessive Current Monitor: The peak value of the Power Supply output current has exceeded 50 (200 for the IP-217A) amperes during a weld cycle. A TROUBLE RESET signal at the I/O connector will be needed to reset the error condition and restore welding capability.
Memory Monitor: When power is turned on, the system will not start. The memory backup battery is discharged and program data has been lost. Press the RESET key to reset the error condition. Replace the backup battery (please refer to Chapter 7) and reprogram the lost weld program data.
The Power Supply will accept the next start signal in an error condition if MR = 0 on the Mode Selection display screen. If MR = 1, the Power Supply will need an error reset to continue. You may perform an error reset from the front panel with the RESET key; or, an error reset signal may be supplied externally through the I/O interface at pins 6 and 7 (refer to Appendix B).