Magnetisation Curve (Synchronous Machines)

  • #1

Main Question or Discussion Point

Hi All,

Today I conducted a lab in which we plotted the open circuit voltage (V[oc]) and closed circuit current (I[sc]) versus the excitation current in the rotor (I[x]).

From the data (plots are attached to thread), it can be seen that saturation occurs in the V[oc] versus I[x] curve however the I[sc] versus I[x] curve remains linear.

Why is it that saturation occurs only with V[oc] and not with I[oc] in the stator?
 

Attachments

Answers and Replies

  • #2
gerbi
Gold Member
174
13
Open-circuit curve (stator voltage vs excitation current) test is performed (or calculated) at zero stator current and 0-1,2 of rated stator voltage. In this case saturation of magnetic circuit is clearly visible.

Short-circuit curve (stator current vs excitation current) test is performed at shorted stator terminals 0-1.0 of rated stator current. Stator voltage (internal stator voltage) is quite low during the test, so you wont observe effects of saturation.

So why saturation is dependent on voltage ? Remember that equation: E=4,44*f*ψ*z
where: E-voltage (stator), f-freuqency, ψ-magnetic flux, z-number of turns

Frequency is static, numer of turs also. Only voltage and flux chanches, so: E≈ψ
The higher voltage, the higher flux is required. Higher flux means higer saturation.
 
Last edited:
  • Like
Likes 1 person

Related Threads on Magnetisation Curve (Synchronous Machines)

  • Last Post
Replies
4
Views
629
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
4
Views
3K
  • Last Post
Replies
5
Views
1K
Replies
2
Views
2K
Replies
1
Views
887
Replies
30
Views
9K
Replies
3
Views
2K
Top