# Contactor with one turn



## QMED (Sep 14, 2016)

What is this? I understand the concept of amp-turns but what would this be used for? I have no idea what it came out of.


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## brian john (Mar 11, 2007)

QMED said:


> What is this? I understand the concept of amp-turns but what would this be used for? I have no idea what it came out of.


A Dashpot, used for Motors OL's and Over Current Protection.


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## JRaef (Mar 23, 2009)

brian john said:


> A Dashpot, used for Motors OL's and Over Current Protection.


 It's been a long time since I've seen one in the wild...


The "dash pot" was a reservoir of oil in a sealed chamber with another chamber above it and a small orifice between them. As current flowed though those coils, it heated the oil, causing it to expand in the one chamber and flow to the other. The time it took for the oil to go through that metered orifice provided the I2t time delay you wanted. This technology was replaced by bi-metal or eutectic melting alloy "heater elements" in motor starters some time around WWII.


The mineral oil used in those was originally laden with PCBs and became illegal even for replacement in the 80s. You could get silicon oil as a replacement, but the other issue was that it was a volatile product and could not be shipped via air freight, meaning you were down for a week or more waiting for it. So whenever an old dash pot sensor went out, they got replaced with something more modern.


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## brian john (Mar 11, 2007)

JRaef said:


> It's been a long time since I've seen one in the wild...
> 
> 
> The "dash pot" was a reservoir of oil in a sealed chamber with another chamber above it and a small orifice between them. As current flowed though those coils, it heated the oil, causing it to expand in the one chamber and flow to the other. The time it took for the oil to go through that metered orifice provided the I2t time delay you wanted. This technology was replaced by bi-metal or eutectic melting alloy "heater elements" in motor starters some time around WWII.
> ...



Pringle utilized Dash Pots dry for no time delay on their early Ground Return ground fault systems.

The other place They were commonly used around here was in Chiller Starters (large motor applications)


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## canbug (Dec 31, 2015)

Thanks for the picture.
I've heard of Dash Pots but never saw one.


Tim.


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## just the cowboy (Sep 4, 2013)

Did it come out that clean, or did you clean it up.


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## MikeFL (Apr 16, 2016)

just the cowboy said:


> Did it come out that clean, or did you clean it up.


It may have been unused spare parts.

Sure look nice!


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## brian john (Mar 11, 2007)

just the cowboy said:


> Did it come out that clean, or did you clean it up.


Most of the Dash Pots I have pulled from Chiller Starters look about like that, the ones from Switchgear not so clean.


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## QMED (Sep 14, 2016)

just the cowboy said:


> Did it come out that clean, or did you clean it up.


I was taking a class, it was in the parts pile.


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