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Clock synchronous motors 50 Hertz

RODALCO

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Mar 27, 2006
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Hello, I am making this synchronous motor thread, to share measurement data from various synchronous clock motors, from electric clocks, I have collected over the years.

I have noticed that these questions sometimes show up in the electrical clock forums.

Most of the clock motors I have are 220/240 Volts 50 Hertz, some are 110 Volts 50 Hertz as well.
Some motors are from electric time switches.

By having Ohm meter readings as well as current measurements from healthy working clocks, this data may help other clock restorers as well.

In this first section I have analyzed a Smiths clock, late 1980's early 1990's. the clock has an USA made Telechron motor for 230 Volts 50 Hz. Coil resistance is around 3.76 k.Ohms, current 3.3 mA at 230/240 Volts AC.

2021-10-13_14-33-53.jpg 2021-10-13_14-34-27.jpg 2021-10-13_14-37-58.jpg 2021-10-13_14-42-54.jpg 2021-10-13_14-43-21.jpg 2021-10-13_14-43-46.jpg 2021-10-13_14-44-07.jpg
 

Mike Phelan

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Dec 17, 2003
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To add to this, none of the data on the stator coil is critical; sticking a resistor in series is a good idea. Wire gauge and number of turns isn't critical at all.

The only thing that is, is whether it's 50 or 60Hz!
 
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shutterbug

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Oct 19, 2005
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Yeah. On this side of the pond, 50 Hz makes for a very slow running clock ;)
 

davefr

NAWCC Member
Nov 29, 2008
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www.telechronclock.com
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To add to this, none of the data on the stator coil is critical; sticking a resistor in series is a good idea. Wire gauge and number of turns isn't critical at all.

The only thing that is, is whether it's 50 or 60Hz!
No, the coil doesn't care about frequency. It's the rotor's gearing that provides the correct speed for a given frequency.
 
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RODALCO

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Mar 27, 2006
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The gearing is the important part. I have some hour counters with 60 Hertz motors in them and they are converted for 50 Hertz with a 6/5 gear ratio to work correct on the lower 50 Hertz frequency.
These low wattage 60 Hz coils don't get to much additional heating with the lower 50 Hz frequency as the power level is to low.
I see if I can find that hour meter to show the visual.
 

RODALCO

Registered User
Mar 27, 2006
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Here I have another synchronous motor, which is used in the German T&N railway clocks to drive the seconds hand, It is a 110/220 Volts with 12k resistor motor 250 RPM runs at 6.1 mA. Type 9904 MB05 13 76.
This motor is also used in certain FNA Ferranti kWh meters to drive the maximum demand registers.


WIN_20211015_12_22_59_Pro.jpg
110 V 50 Hz motor (needs 12k resistor in series to run on 220 Volts) Ferranti
WIN_20211015_12_29_21_Pro.jpg
T&N slave clock movement, motor is underneath the RHS lower brass plate.
WIN_20211015_12_29_48_Pro.jpg
Terminals (double insulated clock motor)
WIN_20211015_12_42_06_Pro.jpg
15 k Ohm is the resistance value of the 110 V motor winding.
WIN_20211015_12_44_53_Pro.jpg
Motor run current at 230 Volts 50 Hz with series Resistor.
 

ElectricTime

NAWCC Business
Sep 28, 2002
254
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I had a client in Hong Kong who purchased a old street clock made by our firm with 115/60HZ motors - he adapted the 230V - but it took me awhile to convince him to purchase the correct frequency motor.
 

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