Dake MEP Tiger 350 Cold Saw VFD Power Question

I just purchased a Dake Mep Tiger 350 cold saw that is 3 phase. I will be connecting a VFD which I have no problem installing and programming. My question comes to the coolant pump and the switch that is connected to the blade handle. I believe that I can connect the handle connections straight to the VFD to S1 and S2. The next question concerns the coolant pump. With the VFD being connected straight to the motor, there would be no power to the coolant pump. I have not checked yet but all indications show that it is 3ph also. So connecting the pump to the VFD maybe possible but how would this turn on and off. Would the handle switch kick this in or would I have to wire it seperate to another VFD. The power lead is currently in a transformer box.

It depends on the VFD and the motors. I use a large VFD (25HP rated) on single phase input and run the hydraulic pump motor (1 HP) for a surface grinder with it. I also have a coolant pump (⅛ HP) for the grinder that I switch on and off separately but wired in parallel with the hydraulic pump motor. That works just fine but the VFD has plenty of overhead for the startup current of either of those. As long as your VFD is sized correctly it shouldn't be a problem.

You have more-or-less three options:

* A second VFD for the coolant pump. $$$.

* A single phase coolant pump. Also $$$.

* You can connect two motors to the same VFD, but you should have a motor protector on each and they will run at the same speed. You also should not start or stop the motors individually unless they are < about 1/10th of the VFD spare capacity.

eKretz said:

It depends on the VFD and the motors. I use a large VFD (25HP rated) on single phase input and run the hydraulic pump motor (1 HP) for a surface grinder with it. I also have a coolant pump (⅛ HP) for the grinder that I switch on and off separately but wired in parallel with the hydraulic pump motor. That works just fine but the VFD has plenty of overhead for the startup current of either of those. As long as your VFD is sized correctly it shouldn't be a problem.

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My VFD is rated for 3hp. The motor for the cold saw is rated 2.5 and the pump motor is 1/8hp so I should be ok running in parallel. I was just wondering if that was possible. I did not want to buy another motor when the pump motor worked fine when I tested the unit on 3 phase wtihout a VFD. Thanks for the reply.

SomeoneSomewhere said:

You have more-or-less three options:

* A second VFD for the coolant pump. $$$.

* A single phase coolant pump. Also $$$.

* You can connect two motors to the same VFD, but you should have a motor protector on each and they will run at the same speed. You also should not start or stop the motors individually unless they are < about 1/10th of the VFD spare capacity.

Click to expand...

I will connect the motors in parallel. The saw motor is 2.5hp and the pump is rated 1/8hp. The VFD is rated 3hp.

Parker1320 said:

My VFD is rated for 3hp. The motor for the cold saw is rated 2.5 and the pump motor is 1/8hp so I should be ok running in parallel. I was just wondering if that was possible. I did not want to buy another motor when the pump motor worked fine when I tested the unit on 3 phase wtihout a VFD. Thanks for the reply.

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If you vary the speed of the main motor, you will also be varying the speed of the coolant pump. That may or may not be a good thing, you would have to assess that.

If you are never varying the speed of the main motor, then there is no problem with doing this, but you MUST also have separate motor overload protection for each motor.