Vane Postion and load relationship

[Centravac]

1. At a recent training provided by carrier, intructor told us that the vane position and amps are directly propotional. If the load is 80 % then amps should be 80 % too. We has Trane R11 and R113 centrifugal chiller that do not work like that. Amps may be 95 % but vane position can be 70 % open. Can someone explain the relationship between the vane position and load on the chiller?
2. We plugged some condenser tubes this year (now 10 % of the tubes are plugged from 4 % last year). We do not have any way to measure the river water flow through the condenser, so we can not quantify how can not perform the calc to see what is the plugging limit. Also, these chillers were installed in early 70s so we do not specs for them. If I were to look at the past trends (condenser pressure, load on the chiller, etc) during peak summer months, can I estimate if the chiller will be able to make it through the summer. We have good data for last 6 -7 years. Any thoughts? Thanks in advance.

 

[TXiceman]

The vane position and capacity or power are not direclty proportional to each other. The control action will be much like you described.

Ken

Ken
KE5DFR

 

[imok2]

As I recall the recommended limit for pluging tubes is about 10%
Assuming that global warming has no effect on your particular area then you should be fairly comfortable with a prediction of upcoming weather trends with 6 past years data.
Normally, the the currnt limit is preprogramed to limit the amount of current that the chiller can load so what I believe the instructor was saying is: EX, say a chiller has a full load amp rating of 300 amps and the current limit is set for 80% then the highest the current it can go to is 80% of FLA or 240 amps but it doesn't have any thing to do with the position of the loading vanes. They may be open to 70% depending on load, head pressure, evaporator pressure, chill water floe ETC.