Figure 1. VSD compressors can save significant electricity costs.
Congratulations, variable speed drive compressors can save you lots in avoided electricity costs — the invention of this type of compressor has helped to save millions of dollars across the world.
These compressors consume only the electricity required of them, they track the compressed air flow up and down and adjust the speed of the compressor to maintain a constant pressure. Here are some tips to ensure your system is running smoothly:
• VSD compressors save power in direct proportion to the flow; this means if you fix leaks, you get the maximum savings, so go out and do just that!
• These compressors like their environment clean, cool and dry. Be sure to keep their surroundings clean and the cooling air filtered. Duct out any excessive compressor room heat (and use it to heat your building).
• VSDs don’t like to run with very light loading. If your compressor is starting and stopping a lot it might be oversized, consult with your supplier.
• VSDs should not normally run at full load, fixed speed compressors are better choices for base loads.
• When running with multiple compressors, the VSD size should normally be equal to or preferably one size larger than the fixed speed compressors with which it must work. If not, the compressors may fight with one another within a control gap. Consult with your supplier about the correct set up to run with other compressors.
• VSD compressors contain sensitive electronics. When they fail, they are not like typical compressors where the replacement of a few inexpensive parts will get them going again. So, plan to have adequate available back up capacity available.
• Like other compressors, VSDs benefit by having large storage receiver capacity with which to work.
• The lower the operating pressure, the more flow the compressors will output per horsepower and the less power these compressors use per unit output. Always try to keep the pressure as low as possible.
You have an Ingersol-Rand VSD in the picture, do you know why their factory settings on their VSD units are at 45% minimal and 70% of full load capacity?
The IR salesman sells it as capable of 75% turn down but it comes set at 45% minimal. I have been told that if the minimal is lowered that the customer looses their warranty. Can you verify these things?
If vsd run full load, compressor will supply max flow, what happen if vsd run with rpm 50%, the flow will 50% of max capacity?