Control device for driving mediate-scale heating furnace fan

Abstract

The invention discloses a control device for driving a mediate-scale heating furnace fan. The problem that a heating furnace fan is difficult to start is solved. According to the control device, a delay relay is connected to the two ends of an alternating current contactor in a traditional control device for the heating furnace fan in parallel, and a pair of normally-closed delay break contacts of the delay relay are connected with a pair of intermediate relay normally-closed contacts in parallel, wherein the pair of intermediate relay normally-closed contacts are connected in a power circuit of the alternating current contactor in series. By optimizing the control circuit, the problem that the heating furnace fan is difficult to start is solved, the heating furnace fan can be started smoothly, and operation protection on the heating furnace fan can be achieved sensitively. The control device is low in transformation cost and good in effect, can be widely applied to start motors of heating furnace fans with the motor capacity being below 120 KW, and has the advantages of being suitable for various loads, high in operation reliability, simple in structure, convenient to maintain and the like.

Description

technical field [0001] The invention relates to electrical equipment in a fan of a heating furnace, in particular to a control device for driving a fan of a medium-sized heating furnace. Background technique [0002] Generally, in order to reduce the starting current of the fan, it is necessary to ensure that the inlet valve is fully opened and the outlet valve is fully closed, and then the fan is started, so that the fan motor starts with a light load. In order to meet the process requirements, the fan of the light oil heating furnace must fully open the inlet valve and outlet valve, so the starting load of the fan of the light oil heating furnace is larger than that of the general fan. In low-voltage (380V and below) systems, thermal relays are often used for motor overload protection, because the protection characteristics of thermal relays are compatible with the allowable overload characteristics of motors, such as figure 1 As shown, the characteristic curve 10 is the ...

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Problems solved by technology

[0009] The purpose of the present invention is to solve the problems existing in the prior art, and to provide a control device for driving a medium-sized heating furnace fan, which can solve the difficult problems of medium-power heating furnace fan start-up and fan operation protection, so that the motor can operate under different load requirements. Under this condition, the starting current of the fan can be avoided, and the protection performance of the original thermal relay can be maintained.

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