I.S. 4146-1983 -Applications guide for voltage transformer’ has recommended the following accuracy classes for various applications.

Applications Class of Accuracy (See Table 1 of IS: 3156 (Part 2) - 1992
For precision testing or as substandard for testing laboratory voltage transformers. 0.1
For laboratory and test work in conjunction with high accuracy indicating instruments, integrating meters and also for substandard for testing industrial voltage transformers. 0.2
For precision industrial metering and for use with substandard indicating wattmeter's. 0.5 or 1.0
For commercial and industrial metering and for use with indicating and graphic wattmeter's and voltmeters. 1.0
For purposes where the phase angle is of less importance, for example, voltmeters. 3.0

It is recommended that the accuracy class should be correctly selected along with correctly determined burden so that the P.Ts can be procured at reasonable price.