View Single Post
Old 23rd Oct 2017, 10:16 pm   #43
Argus25
No Longer a Member
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Variac help please

Quote:
Originally Posted by McMurdo View Post
The only problem with using a timer-bypassed inrush resistor is what happens to the resistor if the timer fails under load. It might get very hot indeed and in a domestic environment might start a fire.
The surface of the power NTC runs extremely hot and needs to, for the resistance to be very low and obviously when using them they must be mounted in a way & place that they cannot cause a fire, even if the NTC melts/disintegrates which can happen, regardless of any additional setups like relay bypass.

Silicon Chip built a very nice soft starter for appliances using this method, you have to subscribe to get the whole article;

http://www.siliconchip.com.au/Issue/...Current+Menace
Argus25 is offline