T
treez
Guest
Hello,
Our contractor designed a 10W, 24Vout, offline Flyback SMPS for 240VAC input. He had a split primary and a bias coil on the primary side, both wound with enamelled copper wire. He also had a secondary of Triple Insulated wire.
He used an SMD transformer which was EFD25 (Page 423 of the below Ferroxcube datasheet).
This failed approvals testing involving testing at 3.5kV for 1 minute.
I am surprised about this, since the secondary was wound with triple insulated wire.
Is it not possible to wind a transformer to pass “3.5Kv for one minute” with the EFD25 transformer?
The approvals house also told us that the PTH version of this transformer would also result in failure. (PTH version is on page 422 of the below datasheet)
The strange thing is that an offline flyback wound on the PQ26/25 core, can pass the “3.5Kv for one minute” approvals test.
Do you know how we can find out which of the transformer bobbins, shown in the ferroxcube datasheet below , can be wound to pass the “3.5Kv for one minute” regulation?
I thought that having a secondary made of triple insulated wire was enough? (obviously including the 8mm primary to secondary gap)
Ferroxcube ferrite datasheet:
EFD25 former is on page 422 and 423....
PQ2625 bobbin is on page 732....
https://www.ferroxcube.com/en-global/download/download/11
Our contractor designed a 10W, 24Vout, offline Flyback SMPS for 240VAC input. He had a split primary and a bias coil on the primary side, both wound with enamelled copper wire. He also had a secondary of Triple Insulated wire.
He used an SMD transformer which was EFD25 (Page 423 of the below Ferroxcube datasheet).
This failed approvals testing involving testing at 3.5kV for 1 minute.
I am surprised about this, since the secondary was wound with triple insulated wire.
Is it not possible to wind a transformer to pass “3.5Kv for one minute” with the EFD25 transformer?
The approvals house also told us that the PTH version of this transformer would also result in failure. (PTH version is on page 422 of the below datasheet)
The strange thing is that an offline flyback wound on the PQ26/25 core, can pass the “3.5Kv for one minute” approvals test.
Do you know how we can find out which of the transformer bobbins, shown in the ferroxcube datasheet below , can be wound to pass the “3.5Kv for one minute” regulation?
I thought that having a secondary made of triple insulated wire was enough? (obviously including the 8mm primary to secondary gap)
Ferroxcube ferrite datasheet:
EFD25 former is on page 422 and 423....
PQ2625 bobbin is on page 732....
https://www.ferroxcube.com/en-global/download/download/11