16.06.2016 Views

Building Services Engineering 5th Edition Handbook

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Electrical installations 293<br />

L1 L2L3 N E<br />

240 V lamp<br />

240 V electric<br />

resistance heater<br />

Transformer<br />

110 V socket<br />

for a portable tool<br />

415 V three-phase<br />

electric motor<br />

13.1 Wiring circuits from a three-phase 415 V incoming supply.<br />

1.00<br />

Relative voltage<br />

0.80<br />

0.707<br />

0.60<br />

0.40<br />

0.20<br />

0.00<br />

–0.20<br />

–0.40<br />

–0.60<br />

V n1<br />

V max<br />

V n2<br />

RMS value<br />

Root mean square of<br />

voltage, RMS,<br />

2<br />

RMS = √ ( ∑V n /N) Volts<br />

= 0.707 × V max<br />

One revolution at<br />

3000 RPM takes<br />

1/50 s<br />

–0.80<br />

–1.00<br />

0 45 90 135 180 225 270 315 360<br />

Phase angle, degrees<br />

13.2 Single-phase RMS.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!