Neon sign transformer

From HvWiki

A transformer used for powering neon signs. Gives high voltage, low current output. The highest typical ratings for these are 15kV, 120mA. Usually the amparage is in 30mA increments. Other common voltages include 10.5kV and 12kV. It is often referred to by the acronym NST.

The transformer contains magnetic shunts which increase the leakage inductance such that operation into a short circuit gives the specified current. The transformer is designed to give continuous operation into any load.

This is the transformer of choice for operating spark-gap Tesla coils, with its high voltage rating and well-defined output inductance.

The output is balanced, with the secondary centre-tap connected to case ground. Some users try to lift the centre tap and ground one output terminal to increase the output voltage. The winding to core insulation is not rated for this abuse, and will break down.

The low output current, falling in the 10mA to 100mA range, means that death is not certain following a shock from the secondary, unlike the certainty from a Microwave oven transformer.