John Schmidt
New Member
- Joined
- Dec 30, 2020
- Messages
- 82
The use of auto transformers has been discussed on Will's, David's and Ian's channels. I've read through countless comment on the topic when use with GroWatt (or any 240v only) inverter, and I remained confused. I was hugely confused by Ian's excellent demo where the 120v bulbs blew when the breaker was tripped. The bulbs blew because the suddenly got 240v, but why did they get 240v? I didn't understand it, and I actually didn't want to believe it (because I had already invested a lot of $$ in equipment). Hope this helps others understand. I won't be using my auto transformers for 120v loads.
I posted on Ian's channel:
I didn't want to believe that using an auto-transformer was going to be dangerous, but I really wanted to understand why those light bulbs blew when the breaker tripped. Below is the explanation. I will be changing to a system that does not require an auto transformer. Thank-you for the time that you took for this excellent demonstration.
Disadvantages of an Autotransformer from: https://www.electronics-tutorials.ws/transformer/auto-transformer.html
1. The main disadvantage of an autotransformer is that it does not have the primary to secondary winding isolation of a conventional double wound transformer. Then an autotransformer can not safely be used for stepping down higher voltages to much lower voltages suitable for smaller loads.
2. If the secondary side winding becomes open-circuited, load current stops flowing through the primary winding stopping the transformer action resulting in the full primary voltage being applied to the secondary terminals.
3. If the secondary circuit suffers a short-circuit condition, the resulting primary current would be much larger than an equivalent double wound transformer due to the increased flux linkage damaging the autotransformer.
4. Since the neutral connection is common to both the primary and secondary windings, earthing of the secondary winding automatically Earth’s the primary as there is no isolation between the two windings. Double wound transformers are sometimes used to isolate equipment from earth.
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I posted on Ian's channel:
I didn't want to believe that using an auto-transformer was going to be dangerous, but I really wanted to understand why those light bulbs blew when the breaker tripped. Below is the explanation. I will be changing to a system that does not require an auto transformer. Thank-you for the time that you took for this excellent demonstration.
Disadvantages of an Autotransformer from: https://www.electronics-tutorials.ws/transformer/auto-transformer.html
1. The main disadvantage of an autotransformer is that it does not have the primary to secondary winding isolation of a conventional double wound transformer. Then an autotransformer can not safely be used for stepping down higher voltages to much lower voltages suitable for smaller loads.
2. If the secondary side winding becomes open-circuited, load current stops flowing through the primary winding stopping the transformer action resulting in the full primary voltage being applied to the secondary terminals.
3. If the secondary circuit suffers a short-circuit condition, the resulting primary current would be much larger than an equivalent double wound transformer due to the increased flux linkage damaging the autotransformer.
4. Since the neutral connection is common to both the primary and secondary windings, earthing of the secondary winding automatically Earth’s the primary as there is no isolation between the two windings. Double wound transformers are sometimes used to isolate equipment from earth.
Show less
