Editing Synchronous motor (section)

==Construction==
[[File:Rotor of an electric water pump.jpg|thumb|right|Rotor of a large water pump. The slip rings can be seen below the rotor drum.]]
[[File:Stator of an electric water pump.jpg|thumb|right|Stator winding of a large water pump]]
The principal components of electric motors are the stator and the rotor.<ref>{{cite web|url=http://www.ece.ualberta.ca/~knight/electrical_machines/synchronous/s_main.html|title=Electrical machine|publisher=University of Alberta|access-date=2013-01-09|archive-date=2013-02-19|archive-url=https://archive.today/20130219194927/http://www.ece.ualberta.ca/~knight/electrical_machines/synchronous/s_main.html|url-status=dead}}</ref> Synchronous motor and induction motor stators are similar in construction.<ref>
{{cite book
 | last = Finney
 | first =  David
 | title = Variable Frequency Ac Motor Drive System
 | publisher = Peter Peregrinus, Ltd.
 | edition = 1991 reprint
 | page = 33
 | isbn = 978-0-86341-114-4
| year = 1988
 }}</ref> The construction of synchronous motor is similar to that of a synchronous [[alternator]].<ref>
{{cite book |last=Theraja |first=B.L. |title=Electrical technology |publisher=S. Chand |year=2005 |isbn=978-81-219-2437-5 |edition=2010 reprint |series=II |page=1490}}</ref> The stator frame contains wrapper plate (except for [[Brushless wound-rotor doubly fed electric machine|wound-rotor synchronous doubly fed electric machines]]). Circumferential ribs and keybars are attached to the wrapper plate. To carry the weight of the machine, frame mounts and footings are required.<ref name="wrap">
{{cite book |last=Isidor Kerszenbaum |first=Geoff Klempner |url=https://books.google.com/books?id=RpmRb1fG8gYC&q=stator+frame&pg=PT47 |title=Handbook of Large Turbo-Generator Operation and Maintenance |date=2011-09-20 |publisher=Wiley |isbn=9781118210406 |edition=Second}}</ref> The synchronous stator winding consists of a 3 phase winding. It is provided with a 3 phase supply, and the rotor is provided with a DC supply.

[[direct current|DC excited]] motors require brushes and slip rings to connect to the excitation supply.<ref>
{{cite book
 | first = Hamid A. Toliyat
 | last = Gerald B. Kliman
 | title = Handbook of Electric Motors
 | edition = Second
 | page = 302
 | isbn = 9781420030389
 | url =https://books.google.com/books?id=4-Kkj53fWTIC&q=synchronous+motor+field&pg=PA302
| date = 2018-10-03
 | publisher = CRC Press
 }}</ref> The field winding can be excited by a brushless exciter.<ref>
{{cite book
 | last = Jordan
 | first =  Howard E.
 | title = Energy-Efficient Electric Motors and Their Applications
 | publisher = Plenum press
 | series = B
 | edition = Second
 | page = 104
 | isbn = 978-0-306-44698-6
| date = 1994-08-31
 }}</ref> Cylindrical, round rotors, (also known as non-salient pole rotor) are used for up to six poles.

In some machines or when a large number of poles are needed, a salient pole rotor is used.<ref>
{{cite book
 | last = Theraja
 | first =  B.L.
 | title = Electrical technology
 | publisher = S. Chand
 | series = II
 | edition = 2010 reprint
 | page = 1404
 | isbn = 978-81-219-2437-5| year = 2005
 }}</ref><ref>{{cite book
 | first = Geoff Klempner
 | last = Isidor Kerszenbaum
 | title = Handbook of Large Turbo-Generator Operation and Maintenance
 | publisher = Wiley
 | edition = Second
 | isbn = 9781118210406
 | url = https://books.google.com/books?id=RpmRb1fG8gYC&q=synchronous+motor+salient+pole+rotor&pg=PT32
| date = 2011-09-20
 }}</ref>

Most synchronous motor construction uses a stationary armature and rotating field winding. This type of construction has an advantage over [[DC motor]] type where the armature used is of rotating type.