df:
日期转时间戳
dtime = pd.to_datetime(df['故障开始'])
v = (dtime.values - np.datetime64('1970-01-01T08:00:00Z')) / np.timedelta64(1, 'ms')
df['start_time'] = v
时间戳转日期
df['故障开始'] = pd.to_datetime(df['start_time'],unit='ms',origin=pd.Timestamp('1970-01-01 08:00:00'))
