A leading UK glass supplier reported that the Blower on its Washer unit wouldn’t run correctly in auto. Our primary objective was to get the system back up and running with a minimum of downtime.
The customer asked whether we could adjust the system to work with the idle mode active, to give added energy cost savings, as during longer periods of downtime the VSD would shut down completely. We were also asked to reduce the ‘Blower cool time’ from 5 minutes to 1 minute, as it isn’t really necessary when using a VSD.
Firstly, the ‘idle to maximum’ speed of the Blower was tested by bypassing the run signal from the PLC panel to the VSD. This proved that the system originally commissioned operated correctly.
The next step was to remove the bypass and test the ‘IDLE ACTIVE’ control. Our engineer removed all the glass from the machine and after the 2-minute period, the run contactor dropped out as designed. Our engineer then had to wait for the 5-minute period for the blower cooling time before the machine was in a condition to restart.
The drive parameter (minimum speed) was altered to 1650 rpm and the operation of relay was changed to send a signal to the PLC when it was at idle. The ‘Blower cooling time’ was then reduced from 5 minutes to 1 minute. The line was then tested throughout the procedure to confirm the operation and to instruct the factory engineers on how the system now operates.
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