14-11-2013, 12:12 PM
I have had a look at the PDF manual that was posted.
It looks like the VFD is most commonly used with a computer equiped with an RS485 port. To get as far as this the RS485 will be switched off. Just don't switch it on.
It looks to me like the VFD has the input set internally to produce the full speed range over the full sweep of the pot without an adjustment. The range is from stop to the maximum the VFD can do and not the maximum range you are calling for.
The pot offers 1 volt per 1000 revs below the stop voltage of 10 volts.
You are using just under a quarter of the full range so this means that for a full sweep control you need to use a pot that covers the range you are going to use and replace the part of the 10k you are not going to use with the fixed resistor.
To get the value you need to connect to the VFD the 10 volt stop signal needs to be reduced to the value that represents the maximum speed you want. All the pot is doing is allowing you to tap off the voltage at the rate of 1 volt per 1k of resistance and the maximum voltage below the 10 volts that represents stop you need for your speed range is about 2 volts. By selecting a 2k pot you get the 2 volt tap when the pot is about 3/4 of full sweep. The other 8k of the pot that you do not require has then to be replaced with a fixed resistor giving the 10k total resistance.
All you have to do is fit the 2k pot as you have done with the 10k pot without making the connection to the ACM terminal. Then solder two bits of wire to the 8k2 resistor and insulate it with a sleeve. Use this resistor and wire to make the connection from the pot to the ACM terminal. This divides the pot into the 2k bit you want to use and the 8k bit that you are not interested in. The VFD will work with pot values of 5k in places where there is a lot of RF noise to 15k in a nice clean area with a screened cable. The resistor in the wire can be varied between 5k and 10k without there being a problem and we will save this task until we have the wider sweep range with the 8k2 resistor in place.
We will be able to fine tune the sweep range of the pot later once you are happy with the improvement you have made with the pot and fixed resistor and you have picked up the experience from implementing it.
It looks like the VFD is most commonly used with a computer equiped with an RS485 port. To get as far as this the RS485 will be switched off. Just don't switch it on.
It looks to me like the VFD has the input set internally to produce the full speed range over the full sweep of the pot without an adjustment. The range is from stop to the maximum the VFD can do and not the maximum range you are calling for.
The pot offers 1 volt per 1000 revs below the stop voltage of 10 volts.
You are using just under a quarter of the full range so this means that for a full sweep control you need to use a pot that covers the range you are going to use and replace the part of the 10k you are not going to use with the fixed resistor.
To get the value you need to connect to the VFD the 10 volt stop signal needs to be reduced to the value that represents the maximum speed you want. All the pot is doing is allowing you to tap off the voltage at the rate of 1 volt per 1k of resistance and the maximum voltage below the 10 volts that represents stop you need for your speed range is about 2 volts. By selecting a 2k pot you get the 2 volt tap when the pot is about 3/4 of full sweep. The other 8k of the pot that you do not require has then to be replaced with a fixed resistor giving the 10k total resistance.
All you have to do is fit the 2k pot as you have done with the 10k pot without making the connection to the ACM terminal. Then solder two bits of wire to the 8k2 resistor and insulate it with a sleeve. Use this resistor and wire to make the connection from the pot to the ACM terminal. This divides the pot into the 2k bit you want to use and the 8k bit that you are not interested in. The VFD will work with pot values of 5k in places where there is a lot of RF noise to 15k in a nice clean area with a screened cable. The resistor in the wire can be varied between 5k and 10k without there being a problem and we will save this task until we have the wider sweep range with the 8k2 resistor in place.
We will be able to fine tune the sweep range of the pot later once you are happy with the improvement you have made with the pot and fixed resistor and you have picked up the experience from implementing it.
