Quote:
Originally Posted by Mike Phelan
I thought ALL rotors on synchronous motors were magnetised  |
You are
the clock expert as far as I am concerned, Mike, but Les Pook says in chapter 3 of his 2015 book;
Quote:
3.2.1. RELUCTANCE MOTORS
A reluctance synchronous motor is a synchronous motor in which the rotor is a temporary magnet made from a magnetically soft material...
3.2.2. MAGENTISED SYNCHRONOUS MOTORS
As the name... implies, the rotor is permanently magnetised. Hence, the rotor poles do not change polarity as the AC voltage on the stator coil changes sign. This means that the stator poles have to be of alternate polarity... The drive to the rotor is smoother than in a reluctance motor so flywheels are not used.
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The clock in question here is a Smiths Deluxe AKA BM7 or BM39. Les describes it as having a "magnetised rotor".
Temco MkI and II movements (and a few others), in contrast, are described as having reluctance motors.
Hope that helps,
Nick.