The MAC diagnosis is an advanced motor-operated valve diagnosis service developed by our company with many years of experience and achievements in the maintenance of motor-operated valves. Comparing a conventional overhaul to an inspection with surgical precision, the MAC diagnosis is comparable to a complete medical checkup utilizing sensor technology. Because the motor-operated valves transmit motor power from the worm, worm wheel, stem nut, and to the stem (valve shaft), the behavior and status of each part will be seen as a change in the torque. The MAC diagnosis accurately measures this torque change during operation to quantify comprehensive soundness in a short period for the check and evaluation procedure.

This enables the disassembly and repair of specific parts only when needed without unnecessarily disassembly of motor-operated valves.

• – Checks the soundness of motor-operated valves quantitatively in a short period of time
• – Abundant experience in diagnosis and high precision operation
• – Measurement of torque during operation
• – Enables readjustment of the torque and limit settings on-site
• – Screening of valves subject to overhaul
• – Prevention of human error
• – Contribution to shortening of periodic inspections and cost reductions
• – Compatible with all motor-operated valves used in domestic nuclear power plants

• – Insufficiency of preset torque value
• – Change in behavior of running torque value
• – Increase of valve pull-out torque
• – Stem nut abrasion volume
• – Motor current value
• – Motor brake operating time
• – Malfunction of electromagnetic switch in control panel
• – Abnormal vibration (such as backlash of transmission system and defect in bearing)
• – Limit switch operation position error
• – Torque switch bypass operation position error
• – Valve stop position error

• Structure of valve actuator and MAC sensor mounting positions（PDF：325.55KB）