In the context of transmission and distribution networks, knowledge of the behavior of instrument transformers in non-sinusoidal conditions is a topic of great interest. Its importance derives from the widespread use of instrument transformers for measurement, protection, monitoring and control applications: their function is in fact to reduce the voltage and current in the network to levels compatible with the inputs of the measuring instruments. The Standards in force require that the performance of measuring instruments be evaluated in realistic conditions. On the contrary, tests on instrument transformers are conducted in sinusoidal regime and at industrial frequency; consequently, their behavior with real waveforms is not fully known. To fill this gap, an architecture has been developed to conduct tests of the behavior of voltmeter transformers (VTs) under traceability conditions, against a relatively large set of static and time-varying waveforms. Following a brief description of the test architecture, the article shows the behavior of two commercial VTs in the face of certain Power Quality events, i.e. amplitude and phase modulations and voltage dips.