What is intermittent duty of a transformer?
The rating required for a transformer operating in an “intermittent” manner in identical, defined cycles is determined from the following formula:
S = √ (tp/(4tc) x Sodb
where:
S – transformer rating
tp – operating time
tc – cycle time
Sodb – rating of the connected load
EXAMPLE: If the transformer output is loaded with 1000VA for 2 s in every 6 s, the rating of the required transformer is:
S = √ (2/6) x 1000VA = 577VA
The phenomenon of intermittent duty is particularly important for the operation of enclosed transformers for power tools. Breve offers products of this type under the PFN name. A detailed description can be found on the website.
