When you notice your Philips steam generator iron steams in intervals instead of continuously, you can find out how this works in the following lines.
Troubleshooting
My Philips steam iron does not steam continuously
The steam boost function is activated
If your iron is a PerfectCare Elite Plus and you are using the steam boost function, then it will not steam continuously. The steam boost function is designed to produce a pulsating steam to tackle difficult creases.
To exit the steam boost function, just press any button.