... 4.core diameter from 220~250mm KY-250D Rotary Blasthole Drilling RigParameterSpecificationsBorehole dia (mm) 250Hole depth (m)17.5Hole direction (degree ... (AC frequency) (kw)75Air compressor motor power (AC frequency) (kw)7.5Total Power Source (kw)390Power Source Voltage (kVolt) 6Transformer Volume ... Stone,Gyratory,Calcite,Clay, Dolomite KY-250D Rotary Blast hole Drilling Rig