Generator switch

[Mooney-Shiner]

Crazy enough, I never noticed that my 67 F model didn’t have a generator switch. I guess I just never missed it.  I fly Cessna for training (getting ratings) and used the alternator on/of switch to opcheck the alternator.

is there a use in having on/off switch on generator?

[Utah20Gflyer]

49 minutes ago, Mooney-Shiner said:

Crazy enough, I never noticed that my 67 F model didn’t have a generator switch. I guess I just never missed it.  I fly Cessna for training (getting ratings) and used the alternator on/of switch to opcheck the alternator.

is there a use in having on/off switch on generator?

I think the most important use is in the case of an over voltage condition you can shut down the charging system to prevent damage to your battery and possibly other things.  

[mooniac15u]

16 hours ago, Mooney-Shiner said:

Crazy enough, I never noticed that my 67 F model didn’t have a generator switch. I guess I just never missed it.  I fly Cessna for training (getting ratings) and used the alternator on/of switch to opcheck the alternator.

is there a use in having on/off switch on generator?

Alternators us an electromagnet so they have a field circuit. The alternator switch turns the field circuit on and off. Generators use a permanent magnet so there's no field circuit to switch on and off.

[MikeOH]

4 hours ago, mooniac15u said:

Alternators us an electromagnet so they have a field circuit. The alternator switch turns the field circuit on and off. Generators use a permanent magnet so there's no field circuit to switch on and off.

Umm, SOME generators use permanent magnets; I do NOT believe Mooneys do.  IOW, you do need current for the generator field.

[47U]

I dug up my IPC for ‘65-‘67 models which has some schematics.  My ‘63 C master switch is a double pole, one side goes to the voltage regulator.  The ‘67 F schematic shows the master switch going to an optional(?) over voltage regulator.  

My C has a load meter in the cluster vs. an ammeter.  Not sure when Mooney changed over.  Regardless, I verify the generator is online by watching the voltmeter (in the cigar lighter) during run up and mag checks.  It should be reading around 14v. 

[N201MKTurbo]

Generators don’t have permanent magnets, per se, they do have some residual magnetism that way it can charge a dead battery. Both generators and alternators have electromagnetic fields. The main difference is the alternator spins the field and the generator has a fixed field and spins the generating element. 
 

In both cases, if you want to test the charging system, pull the field breaker.

[Ragsf15e]

1 hour ago, N201MKTurbo said:

Generators don’t have permanent magnets, per se, they do have some residual magnetism that way it can charge a dead battery. Both generators and alternators have electromagnetic fields. The main difference is the alternator spins the field and the generator has a fixed field and spins the generating element. 
 

In both cases, if you want to test the charging system, pull the field breaker.

Or, if you wanted to shut off your gen/alt, pull the field CB (or shut off the master, but obviously that kills a lot more).

Most VRs (at least newer ones) have built in over voltage protection too.