In most of modern polarimeters and ellipsometers a compensator is present which is used to change the ellipticity of light incident at a crystal in the PCSA system or compensate the ellipticity of light emergent from a crystal in the PSCA system. Most often, a quarter wave plate is used as a compensator. A problem of using the quarter wave plates of which fast axis has to be replaced by the slow one often arises in polarimetric experiments. For this aim the authors study the quarter wave plates made of Gd2(MoO4)3, and DKDP which allow to carry out the mentioned procedure by applying the external electric field to those crystals. In this work the possibility is analyzed for utilizing the compensator of this type in polarimetric investigations with elliptic polarizer. Use of electrically switched compensators in the polarizer-sample- compensator-analyzer system enables to analyze experimentally the 'HAUP maps' dynamics, when changing the output analyzer ellipticity, and evaluate the correspondence of the adopted mathematical model for the polarization scheme concerning the parasitic ellipticities p and q of polarizers.