It may be due to short circuit in the bus bar section of ACB. Currently the protection is outside the busbar. Please give a fuse immediately to the spring charging motor.
Normally spring charge motor is coming with 110V AC/DC type. Please check for spring overload and spring tensions
Most CBs come with a specifically designed motor for spring charging. Good companies provide a fuse to protect the motor if it stalls due to overload, usually caused by some jamming in the spring charging mechanism. If your installation is reasonably new, the manufacturer can be approached to stduy the problem and find a solution.
However, from the tone of your post, i guess it is an old installation, and the manufacturer is not approachable (either closed,or bought by some other company?)
i have come across one long-term failure in DC motors of 110 or 220V. i found that it was imperative to interrupt the supply to the motor on both +ve and -ve leads after it has finished charging the spring. If not, there was a tiny leakage to earth from the one lead which was live, resulting in slow degradation of insulation, and ultimate burnout. No fuse will protect the motor in such a situation.
In summary, if your motor is DC, please interrupt BOTH supply leads by appropriate microswitches/limit switches after it has completed charging. Remember that DC breaking is severe, and special siwtches are available for this duty.
Hope this helps.
Nothing worthwhile can ever be taught, it can only be learnt.
Please check the Spring Limit Switch in your ACB Spring Charging System. Normally, the power supply to the spring-charging motor should be cut-off once the spring gets fully charged. For this purpose, an N.C. Contact of a Spring Limit Switch is used in series with the power supply to the motor. Once the spring gets fully charged, this SLS NC contact will cut off supply to the motor. If the limit switch is not working (contacts jammed) then this motor would continue to get supply. May be the motor is not rated for continuous duty and hence it might burn. However, even when the motor is rotating, further spring charging may be avoided by a latch mechanism in the spring charing mechanical system.