user9253
Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan
|
 Posted: Fri Feb 26, 2010 11:27 am Post subject: What can damage an alternator? |
 |
|
If the OV relay trips off, the alternator voltage could go up when the load is removed. But in order to cause any damage, the voltage would have to be high enough (over 1000 volts) to arc through the winding insulation. How high does the no-load voltage get? With the load disconnected there is no stator current. So the stator winding can not overheat. Even if the field current goes to maximum, it can not be any higher than when the engine is off and the alternator master switch is turned on.
I do not think an alternator can be damaged when the circuit is reset and a full load is applied to an unloaded alternator turning at full speed. Stator current is limited by the load requirements and by the capacity of the alternator. Even if the current was above normal for a few seconds, not enough heat would be produced to damage the windings. What about the huge magnetic forces that try to pull the windings out of position? Those same forces are present in an electric motor when full line voltage is applied to accelerate a motor from standstill to full speed in a few seconds. A motor can draw up to 6 times or more of its rated current when starting. If a motor can withstand those forces, so can an alternator. The two machines are very similar. In my opinion, frequent starting and stopping will shorten the life of a motor or alternator, but occasional tripping and resetting will not.
Below are ways that I think an alternator can be damaged:
Inadequate cooling. (Even an overloaded alternator will not be damaged if kept cool.)
Foreign objects like water or sand.
High field voltage, i.e. trying to operate a 12 volt alternator on a 24 volt system.
Over speeding
Joe
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
Joe Gores |
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
