# Schematic symbol explanation for transformer with arrow through delta winding

While working on a technical drawing for a station supply transformer in a circuit, I encountered this symbol depicting a 1000/230V Dyn transformer. I am not sure what the arrow crossing the delta winding means. Has anyone here had any experience with this specifig symbol?

• never seen that one before, but a diagonal arrow through a component typically means "adjustable" Mar 7 at 10:23

## 1 Answer

I am not sure what the arrow crossing the delta winding means.

Given that this symbol is one that you saw in a diagram of a "station" (assumed to mean a power station) I would say that it incorporates a "tap-changer" on the delta winding. Marcus is generally correct that an arrow means adjustable and a tap-changer is a semi-automated means of regulating the output voltage (presumably on the wye winding). This might help: -

Image from here, along with explanations.

Of course the arrow could imply some other form of regulation or variable capability but, my best guess is that it is meant to imply a tap-changer.

• Sounds correct. I work in the transformer indusrty and we sometimes offer switches on the primary side enabling the lineworker to choose between e.g. 22 kV and 11 kV as is common in Norway. Configurations like these often comes in addition to the tap-changers (e.g. +2-5 x 2.5%). My impression is the symbol could mean either tap-changing or HV changing. But given the primary is 1000V I am sure it is the latter in this scenario. Mar 7 at 11:27
• Do you mean "latter" or do you mean "former"? Mar 7 at 11:31
• I was ambiguous. I meant the "latter-latter" e.g. only tap-changer and not HV-changer. Mar 8 at 6:56