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Special Maintenance List

Ampere-Voltage-Diagnostic Systems "AVD"

What's AVD?
It is the technology to scientifically evaluate the inherent risk which might cause failure and trouble to the motor operated valves. Each plant considers motor operated valves to be extremely important pieces of equipment. Therefore, maintenance to prevent a trouble is required, because once trouble occurs, it could possibly lead to stopping the plant. As the most appropriate means of maintenance, various diagnostics for the motor operated valves have been developed up until now. However, those diagnostic pieces of equipment were not very convenient in terms of operation and safety, and could not perform sufficiently.
Resolving issues in the existing diagnostic technique
once and for all by AVD.

AVD is the remote diagnostic technique system for the motor operated valves
which measure and analyze motor current and electric voltage.


Each Motor-Operated Valve (AC/D)

Diagnostic Mechanism

Wave Pattern Analysis

Check the operation characteristics of the valves based on chronological changes in behavior, and also the location(s) of abnormality.

FFT (vibration) Analysis

Analyze the measurement parameter indicator and detect the abnormality of the rotary part including a gear, the bearing.

Soundness of Drive Ability

Using the design standard value for reference and evaluate whether or not the object valve has sufficient power margin to drive.

Ampere-Voltage-Diagnostic Systems

A set of AVD Diagnostic Equipment

Inspection Items
Abnormality of motorTorque that is generated during the opening and closing of valves
Abnormality of Bearing for MotorPerformance Degradation of Gland Packing
Abnormal Operation of Torque Switch Abnormality of the Valve Disc
Abnormal Operation of Limit SwitchAbnormality of Valve Seat
Deterioration of Torque Spring PackAbnormality of Valve Stem
Vibration during the Motor OperationWear of Stem Nut
Wear of gears and etc.Working Hours/Valve Stem Lift and etc.
Adoption of simple remote diagnosis method

Multiple sensors are required to be installed for the existing type, however, only 2 cables, current and voltage are necessary for connecting to the MCC (Motor Control Center) for AVD.

Existing TypeLarge Small

Main Parameters for Measurement

  • Valve Stem Torque
  • Valve Stem Thrust
  • ValveStroke

  • Motor Current
  • Torque Spring Stress

  • Switch Contact Signal
  • Motor Vibration and etc.

Main Parameters for Measurement

  • Motor Current
  • Motor Voltage
Easily measured, and takes only 15 minutes!!

When using the existing type, expertise in the attachment of multiple sensors to the valve is required for the person measuring complexity, and there were cases of it taking more than a half day to measure one valve including preparation.

On the other hand, no expertise of the measurer is required in AVD, as all he needs to do is to connect 2 cables (current and voltage cables) to the valve, and the measurement can be completed in about 15 minutes, including preparation.

[ Diagnostic Procedure ]

1.Bring the complete set of AVD equipment (with attached case) to the MCC (Motor Control Center).
2.Connect the current and voltage measurement cables to the MCC power cable terminal (clip or clamp).
3.Start automatic diagnosis by opening and closing the valve.
4.The simple diagnostic result is immediately output by the built-in computer.

The number of valves for diagnosis per day

Up to around 3AVD×20
20 (Result Proven)
Effect of decrease in amount of expose to radiation during work

Typically, work has to be performed while remaining close to the valve when using the existing type of equipment. However, when using AVD, direct exposure to radiation is reduced because operations can be performed from a safer distance at the MCC (Motor Control Center). The valve diagnostic activity by AVD largely contributes not only to the “Improvement of Safety”, or reduced exposure, but also improvement of the work environment.