Output Voltage Tolerance

Under rated load, according to EN61558-1, the output voltage may deviate a maximum of 5% from its rated value, 10% on transformers that are inherently short-circuit proof, usually <y 2VA, plus an additional 5% on transformers with rectifiers. For more details - for example, on transformers with multiple output windings - refer to EN611558-1 (2019-12). Note:
The rated values to which the output voltage tolerance and the no-load deviation refer apply to the ambient temperature ta for which the transformer is rated.