| 摘要 |
<p>In a gas valve control system including a microprocessor (5), a first relay (1K), a second relay (2K), a flame sensor (60) and a timer (40) said timer controls a switch (55) which is connected in the power supply path of the second relay. The second relay controls the gas valve (25). Activation of the first relay (1K) causes activation of the second relay (2K) which causes the valve (25) to open. Also, activation of the first relay causes the timer (40) to operate. The flame sensor (60) then must sense flame or else the microprocessor (5) will deactivate the first relay (1K). If the microprocessor fails to deactivate the first relay, the timer (40) causes the switch (55) to open and break the power supply path to the second relay (2K). This in turn causes the valve (25) to close. <IMAGE></p> |
