Primary voltage
The supply voltage applied to the input of the transformer (U1).
Definition
The primary voltage is the supply voltage applied to the terminals of the transformer’s primary winding — in other words, the voltage of the source network. It is denoted U1 and is the first parameter to specify when choosing or designing a transformer.
In Europe, the standard primary voltage is 230 V single-phase or 400 V three-phase (50 Hz). Some industrial environments work at 690 V, 1,000 V or more. For export applications, voltages of 120 V / 60 Hz (North America) or 110 V (Japan) are common.
The turns ratio (n = U1/U2) links the primary voltage to the desired secondary voltage. A discrepancy between the actual mains voltage and the rated primary voltage can cause overvoltage or undervoltage at the output, or even excessive core heating through saturation.
The ABL tip
ABL Transfo offers tapping points (±2.5 % or ±5 %) on the primary to compensate for network variations. If your network is unstable or if you work on several export voltages, state this in your specification — we integrate the tap changers from the design stage.
