Can I Connect Anything in Between a Drive and a Motor?

Wire. What else do you have in mind?

duh I misunderstood the ??

put one of these in

Probably not a good idea....

If you are talking about fuses, disconnects, shunts, and the like, as I have been asked to do many times, it depends. I have several customers that require disconnects between drive and motor with DC applications. For this we use a shunt device to lock the motor when it is disconnected. For fuses and such it isn't needed or wanted between the motor and drive.

NO!!! One should not connect anything between a drive and motor. There are many specific things that one must put between these two, like properly sized and insulated wire. There are many specific things that one may put between a drive and motor depending on the design, like a fuse, disconnect, connectors, surge suppressors, test points, power indicators, relays. There are also many things that one should never put between a motor and its driver. The most important thing one should put between motor and drive is what the documentation from a qualified engineer says to put between motor and drive.

Slight semantic change up here. You CAN connect anything you like between a drive and motor, including tapioca pudding or baby elephants, we do not know your intended task here. That does not however mean that you SHOULD.

Now with that out of the way, it is considered a poor practice to put switching or protective devices in the circuit between a drive and motor, unless there is no other way to get around a safety procedure. Even then, it is generally less risky to OPEN a circuit, but CLOSING a circuit down stream from a running drive is a good way to damage the drive, almost immediately. So isolation switches that are interlocked in such a way as to disable the output of the drive PRIOR to the contacts opening, then prevent the drive from turning on until AFTER the contacts are closed, is about the only acceptable risk one should undertake. Everything else, including fuses, automatic circuit breakers, contactors, tapioca pudding and baby elephants comes with significant risk to all involved parts and parties.

Can I have pink blancmange please?

Sure, if you want a liquid resistance starter between your drive and motor.

What, like a line filter or something? What does the manual say and what were you planning on connecting?

Control should be implemented using the appropriate controller inputs and isolation should be done before the controller not between the controller and the motor.

"I just want to know that can I connect anything in between drive and motor?"

Why would you want to? What is the motive behind the question? Perhaps if you filled us in a bit as to the reason for your question? Why do this? Well, connecting things between a drive and its motor is not typical practice and so the question naturally arises: "Why would you want to? Did you have something specific in mind?"

well, hombre... Sometimes a man's just gotta do what a man's gotta do. Now hitch them koala bears up and let's wrangle some swine.

Hi,

I can only guess that you are talking about connecting a power factor correction capacitor (PFCs) in between stater and motor, as in the conventional starter/motor set-up. For drives, PFCs are a no-no and redundant as well as displacement power factor is of a high value, while in fact distortion power factor which one should be concerned about with drive/motor unit, cannot be corrected using PFCs.

Regards.

Power factor compensation devices at the output of frequency inverters are forbidden as they can be damaged and also damage the drive.

In some cases sinus or du/dt filters are used (to allow longer cables, to protect the insulation of older motors etc.), in such case the filter type must be chosen accordingly to the specs of the drive and usually these filters are provided by the drive manufacturer (though it's possible to use 3rd filters if some specs are verified, especially the PWM switching frequency, also the drive may required a specific parametrization if an output filter is used).

In some some cases, like for example ropeways, a galvanic disconnection, usually a contactor, is installed between the drive and the motor. It must be carefully checked that the drive allows it and that the parametrization of the drive is done accordingly. Typically with advanced drives in scalar mode it isn't much a problem and in non-scalar mode it can be done with some drives (especially advanced ones) if the modulation of the IGBT is interlocked by hardware, i.e. the pulses are locked so quickly that the breaking current of the contactor is not a problem because the mechanical latency of the contactor is higher than the time required to lock the gate drivers. Without interlock the contacts of the contactor can be destroyed.

Of course there are discussions about SIL 3 (PL e) certified torque-off features wich could be a replacement for the output contactor.

In some cases VSD are used only to start and brake a motor while during normal operation at 50 Hz (or 60 Hz) grid frequency the VSD is bypassed. This again requires a specific parametrization of the drive and synchronizing (as well as retrosynchronizing).

Protection devices are normally not installed at the output of a VSD as unless in the rare by-pass example mentioned, the VSD protects the connected motor. The exception is when multiple motors are connected to the same VSD or if a VSD is used to start several motors before those get bypassed (very rare). In such case make sure the protection device is compatible (most electronic motor protection relays are not), some of them look like conventional thermal relays, check the specs).

Usual motor protection devices are note designed for the current type found at the output of VDSs nor are usualy measuring instruments (TRMS devices may work, but that depends on their specs).