The Model 189 is a low ratio wound primary current transformer suitable for primary currents up to 100 amperes. The Model 189 table lists the most common current ratings. Primary terminals for the Model 189: for ratios of 30:5 and below are, No. 10-32 brass screws with one lockwasher (Dimension A=3.28), for ratios of 40:5 and above, 3/8-16 brass studs with one lockwasher and regular nut (Dimension A=4.10).
