Generator DPE (displaced phase excitation)

[theoldwizard1]

DPE is an additional winding on the stator of an AC generator (technically these are called an alternator, but we won' say that here because everyone will think of a car alternator which actually makes DC power and this applies for home/portable generators).

Why is a DPE winding there ? What exactly does it do ?

 

[Muzzy]

I don't really have the physics to explain it, but this is a good start.
https://en.wikipedia.org/wiki/Excitation_(magnetic)

 

[boy1_]

I'm sure somebody with more knowledge will chime in if I'm off track. But I believe it provides power to create the magnetic field the main generator requires to create electricity on non-permanent magnet generators.

 

[ttpete]

I'm sure somebody with more knowledge will chime in if I'm off track. But I believe it provides power to create the magnetic field the main generator requires to create electricity on non-permanent magnet generators.

That would be an exciter. An exciter is a DC generator that excites the rotary field of an alternator. My military 120/240-volt gen-set has a small 12 volt DC generator on the end of the alternator shaft. It excites the field via slip rings. It also acts as a starter motor that uses the battery when the start switch is pressed. And, it's used for charging the battery as well.

 

[Lightning rod]

It’s a separate winding other than the stator (power) windings
That pushes ac volts thru a rectifier and thru slip rings to the rotor so that the rotor provides a fixed dc field to the stator, thereby creating output ac power as the fixed field lines cut thru the stator windings

Generac is the only company that uses the DPE notation for the excitation winding.
Maybe it’s a more correct term since the ac output from the excitation winding is probably not in phase with the ac output windings

This manual gives some theory
https://onan.xmsi.net/00-Other Gensets/86262GS BriggsPortable Generators 1.pdf

 

[theoldwizard1]

It’s a separate winding other than the stator (power) winding that pushes ac volts thru a rectifier and thru slip rings to the rotor so that the rotor provides a fixed dc field (for) the stator, thereby creating output ac power as the fixed field lines cut thru the stator windings/

Generac is the only company that uses the DPE notation for the excitation winding.

Most small AC generator (that I have seen), especially ones with no automatic (electronic) voltage regulation (AVR), don't have a separate "excitation" winding. They just tap off of the main stator power winding, rectify it (make it DC) and maybe pass it through a current limiting resistor and on to the brushes



Of course these excitation windings rely on the residual magnetism in the rotor (field) core to get themselves started !

Maybe it’s a more correct term since the ac output from the excitation winding is probably not in phase with the ac output windings

Ahhh ! Hence is is "displaced" from the main winding