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Zeiss Ernemann VIIIB motor


tompa53
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Hello!

I have installed an Ernemann VIIIB, which is in very good condition. However, I have found that the projector must be run warm and it takes almost a minute until it comes up to full speed. Thought something was wrong with the motor and switched to a spare, but there was no difference. Is this a thing with all Ernemann VIIIB? It simply needs to be warmed up?

 

Perhaps I should add, the projector has been cleaned inside and has new Ernemann oil. Turning the motor manually on the knob is easy. So there seems to be no friction anywhere to cause the slow start.

 

Thomas, Sweden

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Normally these 3 phase motors starts with resistors in die line of each phase, after a few seconds, an relay bridges the resistors an it runs on the 380/400 volts with full power. If this circuit is not working, it runs wth the resistors all the time and works like you wrote.

Jens

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The projector runs on 3 phase. The starter has 2 positions. First about 50% speed with the resistors and then full speed. When "cold", the projector hardly runs at all in the first position and in the second position it needs a minute to reach full speed.

 

If, as you suggests, the motor runs with the resistors at all time, shouldn´t the motor run at reduced speed all the time? And I guess the resistors will be very hot?

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Hello,
do you notice a difference in the engine when switching from the first to the second stage?
If so, then the circuit should be fine. I used to show the VIIb in a country cinema and there was the same problem because the projector room was always cold in winter. We always let the projectors "warm up" for a few minutes. That seems to be normal with these machines.
greetings
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Correct line voltage selected? The 3 phase motor might be connected in star for 380 V, and your line 220V 3 phase. 

Not as common today, but also in Berlin, some districts had 22V IT network until recently. Then motor to be connected to delta.

If that's not the case, measure the voltages on the  motor, they should be close between the 3 phases. If they're not close, check the starter wiring and contactors.

Ernamann 8b used asynchronous drive motors, which were powerful enough to start even in a colder environment. (As Uwe pointed out, the 7b had difficulties in starting from cold, a synchronized asynchronous motor wit lower torque as a reason. Should not be the case with 8b)

 

 

 

 

 

ß

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