Is there an easy way to figure cost of VFD?
You're getting a lot of energy savings information which are great benefits of VFDs on centrifugal loads. But strictly from a straight forward cost standpoint, it's the price of the equipment (contact me off line.. I'll give you budgetary pricing) plus how much time you estimate to mount and wire. (Figure it in days. ie one day, two days, etc). The automation and control is a separate issue. If you're putting a VFD on an inlet vane controlled airhander for instance, you can just use whatever is controlling the vanes to be speed reference of the VFD. But, it can be a lot more complicated than that depending on your situation. If you're going to have to install transducers, or marry it to an existing communication buss. the cost is going up.
One more thing to consider is that not all "standard" machines have sufficient winding integrity to operate successfully on a VFD source. This may entail upgrading the rotating equipment to "VFD-capable" designs, which should pretty much match the existing footprint for 5-25 hp ratings but may not for larger torque capability requirements.
To simplify it down to the absolute basics for a rule-of-thumb approach:
(Upfront costs) + (operation cost for specific period) + maintenance = (lifetime cost).
In the case of existing installed base, upfront costs are (generally) zero.
Therefore, the payback for a new arrangement (VFD, energy efficient, etc) is the time required to "save" the additional costs expended for the transition.
One more thing to consider is that not all "standard" machines have sufficient winding integrity to operate successfully on a VFD source. This may entail upgrading the rotating equipment to "VFD-capable" designs, which should pretty much match the existing footprint for 5-25 hp ratings but may not for larger torque capability requirements.
To simplify it down to the absolute basics for a rule-of-thumb approach:
(Upfront costs) + (operation cost for specific period) + maintenance = (lifetime cost).
In the case of existing installed base, upfront costs are (generally) zero.
Therefore, the payback for a new arrangement (VFD, energy efficient, etc) is the time required to "save" the additional costs expended for the transition.
