S&C automated switches

[Hebrew]

We have a few of the S&C automated switches installed on our system and recently two of them in particular have had the same problem.They close well from SCADA control but for some reason will not open.S&C suggested that the jumpers connecting the switch to hte line might have been too heavy.In one case the jumpers were 250 MCM copper.After changing those to 4/0,the switch worked flawlessly.Then another switch developed the same problem only this time the jumpers were 4/0.Does any one have any of these switches on their system and have a similar problem? Also,could you give me any idea how you have your installation configured?We deadend our conductors on crossarms above the switch then come off the line with Burndy T-taps on the jumper and go to the switch.Overhead conductor is 336.4 AAC and jumper is usually 4/0 copper.Could stability of the pole be a point to consider because when the switch closes the pole gets a very good jolt every time.Thanks in advanced for any reply oan or tips.