FAILURE DIAGNOSIS DEVICE OF ELECTROMAGNETIC SWITCH

To provide a failure diagnosis device of an electromagnetic switch which can obtain a determination result in a shorter time at a time of normal, and can divide a failure part while preventing wrong diagnosis at a time of failure (e.g. including failure of other than the electromagnetic switch of a discharge circuit or the like).SOLUTION: A determination portion 132 composing a BCU 13 determines normal when an absolute value of a gradient of a decrease in voltage is equal to or more than a first threshold value when a first predetermined time elapses after a positive electrode side contactor 121 is controlled to open, determines failure when the absolute value of the gradient is less than the first threshold value, determines welding failure of the positive electrode side contactor 121 when the failure is determined, a second predetermined time longer than the first predetermined time elapses, and the absolute value of the gradient of the decrease in voltage is less than a second threshold value smaller than the first threshold value, and determines failure of other than welding of the positive electrode side contactor 121 when the absolute value of the gradient is equal to or more than the second threshold value.SELECTED DRAWING: Figure 1 【課題】正常な場合には、より短時間で判定結果を得ることができ、異常（例えば放電回路等の電磁開閉器以外の異常を含む）な場合には、誤診断を防止しつつ、異常箇所の切り分けをすることが可能な電磁開閉器の異常診断装置を提供する。【解決手段】ＢＣＵ１３を構成する判定部１３２は、正極側コンタクタ１２１が開くように制御された後、第１所定時間が経過したときに、電圧低下の傾きの絶対値が第１しきい値以上の場合に正常と判定し、傾きの絶対値が第１しきい値未満の場合に異常と判定し、異常と判定した場合には、第１所定時間よりも長い第２所定時間が経過したときに、電圧低下の傾きの絶対値が第１しきい値よりも小さい第２しきい値未満の場合に、正極側コンタクタ１２１の溶着異常と判定し、傾きの絶対値が第２しきい値以上の場合に、正極側コンタクタ１２１の溶着以外の異常と判定する。【選択図】図１