I've a small question regarding how to connect the terminals for 220V output. As per the diagram in below pic my understanding is :

Output terminal H1& H4 Output 220V: H1-H2=shorted & H3-H4= shorted output 440V: H2&H3 shorted

Is this correct? I don't want to make any wrong connections and blow up things.Also the label says 0.120kVA & 0.150kVA for 220V and 440V respectively. What does that mean? How much max curent can be drawn from this transformer safely?

Thanks. Transformer IMG 1

Transformer IMG 2


2 Answers 2


Not quite. The connections would be as follows:

  • For 440-480V you would connect H3 and H2 together.
  • For 220-240V you would connect H1 to H3, and also connect H2 to H4.

I've cleaned up the diagrams to make it clearer:

240V             480V

The location of the terminals in the diagram correspond exactly with the location of the terminals on the transformer, despite the fact it looks like two are reversed. The reason for them wiring it with a cross-over like they have is that the connections can then be made to adjacent terminals using bus bar as has been done in your picture.

The rated powers are as follows:

  • 0.12kVA when driven from a 50Hz source
  • 0.15kVA when driven from a 60Hz source
  • \$\begingroup\$ Thanks mate. My input voltage is 120V @ 60Hz. Everything is clear now :) \$\endgroup\$
    – RSB
    Apr 26, 2017 at 16:13

It is currently wired for 440/480V with the shorting bar between H2 and H3.

For 240V you should REMOVE that jumper and short H1-H3 and short H2-H4. The 240V is drawn from those two points.

The power capability is stated as 0.120kVA at 50Hz and 0.15kVA at 60Hz.

If your output voltage is 240VAC at 60Hz you can draw maximum 150VA/240V= 625mA.

If you don't jumper H1-H3 and H2-H4 you will get two independent 240VAC outputs (from H1 to H4 and from H2 to H3), each with half the total capability.


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