At the moment I am a little baffled!!!!
I have been asked by an electrician friend why a standard "Obis" time switch is GAINING time. For about 5 years it set automatic door locks at a residential care home and had been working perfectly until recently when it started to gain about 25 mins every 24 hours.
There is nothing special about it, no "electronics" just a disc magnet with pole pieces mounted in a little iron frame with a mains operated coil for excitation.
there is the usual gear train and cam system to operate the switches and it really could not be more basic.
An identical one is in another block and works perfectly.
Now I can understand how for various reasons it could run slow, but as I see it, the only way it could gain time was if the "mains" frequency (50Hz) increased which would then affect the other clock as well.
Any ideas anyone??
I have been asked by an electrician friend why a standard "Obis" time switch is GAINING time. For about 5 years it set automatic door locks at a residential care home and had been working perfectly until recently when it started to gain about 25 mins every 24 hours.
There is nothing special about it, no "electronics" just a disc magnet with pole pieces mounted in a little iron frame with a mains operated coil for excitation.
there is the usual gear train and cam system to operate the switches and it really could not be more basic.
An identical one is in another block and works perfectly.
Now I can understand how for various reasons it could run slow, but as I see it, the only way it could gain time was if the "mains" frequency (50Hz) increased which would then affect the other clock as well.
Any ideas anyone??
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