May I ask, experts: why does a steam turbine governor have a minimum operating speed?
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As the title suggests, in a 505 speed control system or other such systems, the governor starts to function only after the turbine speed reaches, for example, 8000 revolutions per minute. I don’t understand why this is the case 505 is an electronic speed control system; theoretically, it should be able to operate from 0 revolutions per minute to 11,000 revolutions per minute, and the speed controller can be used for adjustment. I’ve never been able to figure this out. Please explain, thank you.
I don’t understand; weren’t many tests carried out using 505 during low-speed warm-up? How is it possible to reach 8,000 revolutions?
During low-speed warm-up, the governor does not participate in the control; it is only when the speed reaches 8,000 revolutions per minute that the governor starts to function. This is an electro-hydraulic speed control system – why is a threshold of 8,000 revolutions per minute set?
This problem also exists; with the 505-equipped units (Hangzhou Motor), it was the same case – after warming up at low speed, the speed had to be increased manually beyond the critical speed before automatic control took over. The units I’m working with now don’t have the 505 component, and this issue doesn’t occur there as the control is automatic. I’m not sure what the difference between these two types is.
I used to work on mechanical governors; only after filtering out the minimum speed could the governor engage its brake. You can take a look at the schematic diagram for more details.
What you’re referring to is probably a governor that is mounted on the turbine shaft. In the case of the 505 electro-hydraulic governor, the oil supply comes directly from an electric pump, so there is no issue of insufficient oil pressure at low speeds.