First, for convincing your boss, I would just point out that wattmeters take into acount power factor. If you have a portable wattmeter, you could quickly wire up a 1hp motor and show the difference between what you calculate with your amps and volts (VA) and what the wattmeter shows.
Second, is the cost of downtime less than the extra power cost? I sure doubt it. It would seem that your boss should be comparing the extra cost of power, the cost of keeping spare parts on hand, and the cost of downtime. I would think that the end result is to fix the cap bank and keep some spare parts on hand for the future. That is where the discussion would be in my plant. Keep running to keep the customers happy, get it fixed quickly, and then prevent the problem in the future.
Second, is the cost of downtime less than the extra power cost? I sure doubt it. It would seem that your boss should be comparing the extra cost of power, the cost of keeping spare parts on hand, and the cost of downtime. I would think that the end result is to fix the cap bank and keep some spare parts on hand for the future. That is where the discussion would be in my plant. Keep running to keep the customers happy, get it fixed quickly, and then prevent the problem in the future.