EMCO V13 VFD ISSUE.

It is a bit complicated, in addition there are different schematic versions of the V13 some with 2 speed motors and an electric motor brake. Below is the basic version with a single speed motor, what appears odd is all the controls and switch gear seem to be run off of line voltage, typically you see a step down transformer. The VFD you have will not work even if directly connected to the motor, it is rated for 2 Hp on single phase, you would need something like the Hitachi WJ200-022SF which is commonly used. You could use the KBAC for a grinder or similar 3 phase motor. On the diagram below L1 and L3 drive the switch gear so this would be between the two line legs (not a generated leg like on a RPC), these would also be used to provide power to the VFD at either A1 or C1 (U, V, W terminals).

An RPC can power the unit directly, most likely want to go with a 7.5Hp, something like the SB-7, but a bit pricey and soem complain of the motor whine. A few individuals have gone with the American Rotary AMP which is a self contained plug and play type of RPC, they are also very quiet. If you plan on additional 3 phase equipment you may want to go with a larger RPC. Also be mindful that the generated wild leg should be connected to L2 in the below schematic.

One approach I have taken with if you want to go the VFD route has been to remove the high voltage wiring to the contactors and just use one set of contacts to trigger the forward direction and the other contactor to trigger the reverse direction using VFD low voltage inputs. All the other controls will work the same on the lathe, the motor is directly connected to the VFD outputs. Now the issue is that old contactors, the contacts are typically pretty crispy and have a high contact resistance, this does not work well with the low level signaling used in a VFD (typically 24VDC and a few mA). So would need to replace the FOR/REV contactors with new units or just plain old relays would work. Some examples below the revised documents are toward the end or PM me and I will send them to you.


Maximat V13 Scheamtic.jpg
 

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Well, we got it runnning…….not sure why you said it is rated for 2 HP when everything I read says 3? But you were certainly correct:” Now the issue is that old contactors, the contacts are typically pretty crispy and have a high contact resistance, this does not work well with the low level signaling used in a VFD (typically 24VDC and a few mA). So would need to replace the FOR/REV contactors with new units or just plain old relays would work. Some examples below the revised documents are toward the end or PM me and I will send them to you.” He went around them but I have no reverse……..and as you posted, my son said we need to get some new relays to get it working as it should.
 
An aside: I put the EMCO 4 jaw self centering chuck on the machine and put a clock on a 1/2 carbide endmill and as far as I can see with my naked eye there is NO run out………I will try using a digital one later.
 
when you install a vfd, you always take out the contactors. There should be nothing between the vfd and the motor. The original switches control the VFD, the VFD controls the motor. With contactors on the output side of the vfd, between the vfd and the motor, you will destroy the vfd in short order.

this is my V13

51117979422_e68a0777a1_c.jpg


Does your motor have a brake?
 
Thanks for that.......sent it to my son. I dont know about a brake?
 
Cant you just put a magnetic contactor to the on switch to power the vfd up. Then use the low voltage side to go to the for/rev contactors and set up a 10k pot for the speed control. Thats what I did on my v13.Forget about all the other switches.
 
The Emco already has a contactor for power up that would be wired to the VFD input, only reason for this is if you do not have a main power disconnect switch. The discussion was/is was to replace the contactors with new ones or relays, strip out the high voltage wiring and just use them to switch the VFD low voltage run inputs. You need new contactors/relays because of the increased contact resistance of used ones. Also as previously mentioned, some Emco motor versions have an electo-mechanical brake on the motor, this needs to be removed if one is going to use VFD braking. Lathes that use a mechanical brake need to also issue a free run command to the VFD if retained and also need to break the run command so the lathe doesn't restart upon release of the brake. There are a number of ways to do this, this approach has also been outlined in this post which is probably the simplest unless you want to rewire the lathe and build a new control system:
 
I use the original power switch on my v13 to switch on a contactor, which provides switching for both legs of the 240v to the input side of the vfd. The switch itself is simply not rated for the amperage required by the vfd/motor on single phase.

The switch also controls the power input for the 24vdc 5a power supply. The power supply is used for the main contactor coil, as well as the brake coil in the motor. The vfd controls the brake via a relay, as the relay inside the vfd cannot handle the amperage of the brake. The brake is off when energized. Yours may not have a brake. Can you turn the motor without power applied to it? If no, then you have a brake.

From the factory, the brake is wired to one phase of the motor inside the terminal box on the motor itself. When the motor recieves power, the brake is energized and releases. When power is cut, the brake applies. There are two small wires for the electromagnetic brake coil. Bring those out and up to the main box and hook to a relay controlled by the vfd.

You'll have to play with the programming in the vfd to get the brake to act like you want, but I really like it.
 
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