| 摘要 |
PROBLEM TO BE SOLVED: To provide an insufficient voltage detection circuit suitable for a pump controller that controls a liquid level of conductive liquid stored in a liquid tank to a desired state.SOLUTION: An electric pump controller is configured such that AC voltage decreased while insulated via a transformer 20 from an external AC power source is applied to each of electrode pairs 21, 22, and 23 for detecting a liquid level of conductive liquid 2 stored in a liquid tank 1 and, based on liquid information on the basis of the conduction states of these electrode pairs, the liquid level is controlled to a desired state via the electric pump and an invertor 5 that drives the electric pump at a variable speed. An insufficient voltage detection circuit 30 is configured to detect that a DC voltage obtained by rectifying decreased AC voltage has decreased below a preset determination value. When the insufficient voltage detection circuit 30 detects the decrease in the DC voltage, a determination is made that the external AC power source went out, and various pieces of information about the electric pump controller are stored in an EEPROM 13 as a non-volatile memory. |
