Hello

We protect equipment from overload with a Coupling or Adjustable Speed Drive between the motor and the load. The product known as MagnaDrive, works with rare earth magnets. These rare earth magnets drive the torque through a gap of air. The drive train becomes a 'disconnected connection'. It's this 'disconnected connection' that

protects the system from overloads.

More can be found at www.magnadrive.com

MagnaDrive have agents across the globe. If you are based in the UK or Ireland make contact with me.

Frank Holden. ■

I caution you on Magna Drive. We have built simulation models of the Magna Drive in all of its forms, at the request of a client required to use them in South America.

There are models and conditions where it can deliver 250-300 % of rated full load torque. Variable air gap can do it. Fixed air gap not so much. It depends on the application.

If you wish to know more, contact the undersigned. Presently, this is a touchy subject between two clients. We do not wish to diss Magna Drive, just know how to apply it and know when it may harm more than help. ■

Originally Posted by sganesh

Dear Mr.Frank,

What is the relation between the normal load ampere and over load relays setting in the conveyors where your Magna drives are installed?

Regards,

For Normal Induction motors,

The setting of overload is to trip the motor in case of continuous overload.Normally the motor has at least 20% surplus capacity.

Hence generally the overload is set at 80%.

Incase of HT motors delayed action fuses(HRC) are installed to protect against short circuit in the system.Due to delayed action there will be no tripping during starting (Starting current is 6 times full load current). If due to any reason, one fuse blows out,all the three fuses including the healthy one should be replaced.

In case of LT motors tripple pole MCCBs are deployed for protection against short circuit.

Rgds,

Narayanan Nalinakshan. ■

Power supplies often have protection from short circuit or overload that could damage the supply or cause a fire. Fuses and circuit breakers are two commonly used mechanisms for overload protection. ■

Originally Posted by yogeshmach

Power supplies often have protection from short circuit or overload that could damage the supply or cause a fire. Fuses and circuit breakers are two commonly used mechanisms for overload protection.

Dear Friends,

I have not come across Magna drive.Have any one installed one in India,so that, we in India, can have some experience.

Though HRCfuses and Circuit breakers are primary equipments for motor protection,there are special motor protection relays,which can store details of tripping and causes.

The characteristics of the motor is essential for selection of these relays.

The protection of HT motor and LT motors are different.Fuses are normally not used in LT motor circuit,for fear of single phasing, MCCBs are the best choice instead of HRC fuses.If the motor characteristics are given,the relay manufacturer can select the best protection system.

Rgds,

Nalinakshan. ■