S Drives running hours

Fraud by the re[air ccompany? who does routine service after a certain number of hours of operation, or someone invoices you for machine operated hours?

I am not sure if this is what you imply. You seems to imply that one means of measuring the operating hours gives you about half the time of the other.

I then wonder who gains in this? Why do you need to measure these hours?

WGAS

I think you have connected the analog hour meter to the brake contactor, which means the analogue meter will get input only when brake contactor is on.For you to get the total hours run you should connect the analog meter to the main contactor.

Ramvinod is correct. You may need to observe the controls as they operate and parallel the main contactor coil circuit. When it energizes, your counter energizes.

Good luck,

James

Generally speaking... on most cranes or hoists, to release the brake you have to energize it, so that it will fail safe and hold the loads on the failure of the control system. So putting an hour meter across the brake contractor is more then likely a valid approach.

The difference in the two recorded times is more then likely from the fact that your analog meter records, "moving" time where as the drive may record "power on time" and will record the passage of time even when the motor is not moving.

Can you elaborate , i could not understand properly

By connecting only to the brake contactor, the ETM (Elapsed Time Meter) is accumulating time only when the drive is allowing a move, i.e. the brake is released. In most hoist drives, the drive must energize the motor prior to releasing the brake so that the load does not drop while the drive is attempting to create enough torque to stop it. In fact, if the load is already moving (dropping), the motor may be unable to create enough torque to overcome the inertia! So the motor is energized while to brake is still engaged, the drive goes through a routine as it determines the proper output algorithm to maximize torque so as to hold the load, then the brake is released and the drive is in firm control. It is called a "torque proving" command. The difference as far as the ETM is concerned then is the difference between run-time of the drive and movement-time of the load, because by being tied to the brake release, it is only tied to the movement-time.