Knowledge and practice about Manipulation element (be operated pneumatically, hydraulically or electrically, control valve), knowledge basic control engineering ( positioner, actuators, DC servomotor, AC servomotor,hydraulic ram servomotor, ON OFF control system, alarm setting, various automatic control system, operation mechanism as sensor, controller, transducer/converter,  positioner, regulator, control valve, actuator, relay, servo motor). Knowledge and practice operate system can b tested : main engine, power generator and distribution, boiler, auxiliary machinery, Knowledge and practice uses digital analog multimeters (accuracy, battery, resistance, voltage, current, diodes), protective/safety device isolated (used insulation tester, continuity tester, digital and analog multimeter, clampmeter ),