In a stand alone PV system, inverters are frequently used to change the direct current (DC) from a battery bank to 230-volts, 50-Hertz(Hz) (In USA and Canada 120-volts, 60 Hz) alternating current(AC).The conductors between the inverter and the battery must have properly rated over current protection and disconnect mechanisms [NEC 240,690-8b(3), -8(b)(4),-15]. These inverters frequently have short duration (tens of seconds) surge capabilities that are four to six times the rated output.

For example, a 2500-watt inverter might be required to surge to (2500x4)10,000 volt-amps for 5 seconds when a motor load must be started. The NEC requires the ampacity of the conductors between the battery and the inverter to be sized by the rated 2500-watt output of the inverter. Consider a 24-volt system, a 2500 watt inverter would draw 134 amps (2500/0.85/22) at full load (85% inverter efficiency and 22 volt battery charge. The ampacity of the conductors between the battery and inverters must be 125% of the 134 amp or 167amp.

This 167amp current in conductor is at the ambient temperature 30°C. Normally the inverter operates at temperature at 40°C to 45°C so derating of cable be must. Go to NEC table 310.16 and select 60°C column, where you find derating correction factor 0.71 in the right hand side of 41-45 ambient temperature. Devide 167 by 0.71 you get corrected 235 amp and conductor size 300 kcmill.

The length of conductor should be kept small to avoid voltage drop. The conductor should be tested for voltage drop also (continue).

## Tuesday, May 18, 2010

Subscribe to:
Post Comments (Atom)

## 6 comments:

Good post very interesting

Good post very interesting

The length of conductor should be kept small to avoid voltage drop.

The length of wire is necessary to consider the

Your blog article is very interesting and fantastic,at the same time the blog theme is unique and perfect,great job.To your success.

Inverter Battery

Hello, I enjoy reading through your article. I like

to write a little comment to support you.

my web-site :: pay day loans

Post a Comment