Quote Originally Posted by Segei View Post
I agree that energy savings is very interesting and complicated issue.
About proven methods. 1,2 are always right for compressors, but are not always right for the plant. I didn't get about monthly peak 1/2 KWh and bearings? Recently, I heard that VFDs spikes can damage the motor bearings.
In many places the energy supplier charges the customer on the highest kWh during any 30 minute period of the month, so in this case you would be charged the same if you had the plant shut down for 27 days and only ran the plant for 30 minutes as you would if you ran the plant all month. There is usually peak (spike) in power consumption for say a commercial building when the AC starts in the morning and another in mid afternoon when the load is higher. These charges are to pay for the maximum size of power cable required to transmit the electricity from the power station to cover the I2R losses. Power factor increases the I2R losses for inductive loads so there is a penalty charge for that too. Some large power consumers use power factor correction (big capacitors) to minimise the penalties.
Quality VSD's like Danfoss correctly installed and commissioned have good protection from spikes and bearing damage.
Compressors are usually the largest power consumers and their efficiency is very important. I have seen chiller COP as high as 18 in Sydney using the Turbo Cor.
In Aus NABERs will become regulation in August forcing most buildings to list energy ratings. There are new products like Building IQ which can override control systems to ensure maximum efficiencies using live weather data for load matching and much much more. Energy efficiency is my favorite subject and career.