| 摘要 |
PURPOSE:To suppress air quantity variation to a small value when power source is switched from V-power source to C-power source due to the fault of the V- power source by making it possible to select the opening degree of a damper at a time when the operation is carried out using the V-power source responsive to the load. CONSTITUTION:When V-power source 5 is in fault, and switches 2-4 are changed over to ''open'', ''open'' and ''close'' to start the operation using C-power source, the opening degree of the damper 9 varies toward a damper opening degree 14x. The difference 17x-14x between damper opening degrees is a function of the load air quantity x%, and the time required for the variation is also a function of x%. On the other hand, the time required for increasing from the V-power source operation rotational speed nx to the C-power source operation rotational speed ns is a function of the load x% because ns is fixed to 50Hz or 60Hz. The output curve is selected by a function generator 15 in conformance with the rotational speed varying time. As a result, even when the V-power source is in fault, and changeover to the C-power source is carried out, the increase in the rotational speed and the throttling of the damper are carried out at times substantially coincident with each other. |
