| 摘要 |
PURPOSE:To check the operation of a control water level sensor frequently without stopping the operation of a boiler system and to detect a fault securely, by checking the operation of the sensor when the 2nd preset reference value is attained, and utilizing the relation between the lowering speed of the water level in a can and a cumulative heating period. CONSTITUTION:When the water level in the can which rises when water is fed attains to an upper-limit water level H, an upper-limit water level probe 3b put away from the water surface is immersed in the water, so that probe 3b conducts to an underwater electrode 3c and a current flows through the 2nd current detector 3f. The output signal of the current detector 3f is inverted from ''0'' to ''1'' and an upper-limit water level signal SH is outputted (g) to reset a flip-flop 4b (h), so a relay 4d is unenergized to stop a feed water pump W. When the feed water is stopped, the water level in the can drops (i) and reaches a lower-limit water level L (b'), and the 1st current detector 3e operates (c') to set the flip-flop 4b again (d'), starting feeding water. |
