Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
1Development of MHPS-TOMONI® Motor-Driven Equipment
Diagnostics System

TAKASHI SONODA*1

YASUSHI MORISHITA*2

HIROYUKI WATANABE*3 KAZUHIRO TSUYUKI*4

Motor-driven rotating machinery has been used in various industrial applications, but themaintenance of such machines has been time-based inspection in many cases. A vibration meter isgenerally used to diagnose the condition of rotating machinery, which requires the installation ofsensors, cable work, etc., on site, resulting in increased costs. Mitsubishi Hitachi Power Systems
Ltd. (MHPS) developed a motor-driven equipment diagnostics system, which diagnoses thecondition of rotating machinery and motors through a simple system in which a clamp-type current
sensor is installed on the power cable for driving the motor and furthermore presents diagnosis
predictions (of one year later). With this system, persons in charge of maintenance can easily plan
the maintenance of rotating machinery and motors with quantified indicators based on the resultsof diagnosis predictions, and excessive maintenance costs can be reduced.

|1. Introduction
Motor-driven rotating machinery has been used in various industrial applications, but themaintenance of such machines has been time-based inspection in many cases. A vibration meter isgenerally used to diagnose the condition of rotating machinery, which requires the installation ofsensors, cable work, etc., on site, resulting in increased costs. The motor-driven equipment
diagnostics system developed by MHPS diagnoses the condition of rotating machinery and motors
through a simple system in which a clamp-type current senser meter is mounted on the power cablefor driving the motor and furthermore presents diagnosis predictions (of one year later), andindicators that can be used in maintenance planning and contribute to the reduction of excessive
maintenance costs are quantitatively displayed/presented as part of the MHPS-TOMONI® Cloud
Service.

|2. Maintenance inspection of motors at thermal power plants
At a thermal power plant, a number of rotating machinery are operated, but the maintenanceof many such machines is actually Time-Based Maintenance (TBM), not Condition-Based
Maintenance (CBM). We acquired the overhaul records of motors (125 cases in total) at a power
plant and investigated the frequency of the occurrence of anomaly for each part of the motors. The
results showed that no anomaly occurred with the stators and minor anomaly occurred with 19% of
the rotors and 26% of the other parts. Figure 1 shows the appearance of each part of the motorinvestigated. Figure 2 lists the number of anomaly detected for each part. These investigation
results revealed that 60% or more of all the motors were returned after their consumable parts(bearings, gaskets, bolts, coating, etc.) were only replaced by the maintenance company. It isexpected that 60% of the maintenance cost could be reduced if the maintenance of motors wasshifted from time-based maintenance to condition-based maintenance.
*1Senior Manager, Service Engineering Department, Research & Innovation Center*2

Deputy Director, Project Engineering Department, Power & Energy Solution Business Headquarters, Mitsubishi Hitachi Power

*3

Nagasaki Plant Engineering Department, Project Management Division, Mitsubishi Hitachi Power Systems,Ltd.

*4System Development Group,Intellectual Production Management Department, MHPS Engineering Co.,Ltd.

Systems,Ltd.

Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
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Figure 1

Appearance of each part of one example motor

Figure 2

Number of anomaly for each part of the motors|3. Motor-driven equipment diagnostics overview
Figure 3 gives one example of a motor-driven equipment diagnostics system. For each part,
specifically the (1) motor, (2) transmission device and (3) rotating machine body, of the
motor-driven equipment, the change with time diagnosis results and the diagnosis prediction
results (of one year later) based on the diagnosis results are monitored to prevent equipment
problems at a thermal power plant. Persons in charge of maintenance can use both daily diagnosis
results and prediction results in maintenance planning, select the parts of the equipment to be
maintained based on the condition data and make a maintenance plan targeting both the preventionof problems and the reduction of costs.

3.1

Web screen on MHPS-TOMONI®

Figure 4 depicts the motor-driven equipment diagnostics service web screen. The screen
consists of three layers. The first layer displays the overall conditions of the entire equipment forsix months ago, five months ago, four months ago, three months ago, two months ago, one month
ago and the present, as well as the predictions for half a year later and one year later, in five levels,
to allow an overall evaluation. The second layer displays the present conditions and the prediction
results of half a year later and one year later of the (1) motor, (2) transmission device and (3)machine body of the selected equipment in five levels. The third layer displays the time-based
evaluation data of each part of the equipment including the predicted values. In addition, the data
analysis results are displayed and visualized using two-dimensional coordinates with two related
variables selected from items (1) to (3) to show future prediction behaviors clearly.

Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
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Figure 3 One example of MHPS-TOMONI® motor-driven equipment diagnostics System(equipment number of remote monitoring is from four to twelve equipments)

Figure 4 Example of motor-driven equipment diagnostics web screen

3.2

Introduction of simple remote motor-driven equipment diagnostics service

Figure 5 illustrates the service system in which the motor electric current data measured by
the customer is diagnosed and analyzed on the MHPS-TOMONI® platform. This service system
uses a rental set of electric current measuring devices (clamp on meter, data processing unit, tablet,etc.), so that the customer can introduce the system at a low cost. (Limited to 50 sets/month.)Monthly trend monitoring of diagnosis is performed and the results can be used in the study ofreplacement time. The screen of the tablet and the data processing unit are shown in Figure 6.

Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
4Figure 5 One example of MHPS-TOMONI® simple remote motor-driven equipment
diagnostics system

Figure 6 Component examples of simple remote motor-driven equipment diagnostics system|4. Examples of diagnosis by motor-driven equipment diagnostics
Evaluation examples of the detection anomaly signs obtained by motor-driven equipment
diagnostics are described below.
(1) Detection of motor rotor anomaly
In the diagnosis of the motor-driven equipment conducted at a power plant, the motor
rotor was diagnosed as being anomaly. The results of the overhaul conducted during a regularinspection by the motor maintenance company are shown in Figure 7. It revealed that there
were multiple dent flaws on the rotor visually. The rotor was replaced with a non-defective one,and as a result, the electric current of the motor being operated was diagnosed as being in agood condition. Diagnosis of before and after regular inspection by motor-driven equipment
diagnostics also showed the condition of the equipment was improved.

Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
5Figure 7(2)Detection of motor stator anomaly
Figure 8 is an example in which a sign of anomaly of the motor stator was detected fromthe remote monitoring data. The evaluation value of the three-phase current balance (Iub)showed an increasing trend, and we recognized that the motor stator was in a condition wherereplacement would be recommended one year later.

Figure 8(3)Anomaly of motor rotor detected by motor-driven equipment diagnostics

Motor stator anomaly detected by motor-driven equipment diagnostics

Detection of belt looseness
Figure 9 presents an example in which an anomaly loosened belt of the transmission
device was detected by this motor-driven equipment diagnostics. Before belt adjustment, there
was a high peak value (-38dB) in the loose belt frequency zone in the FFT analysis of the motor
current value. After belt adjustment (tightened as per threshold value), the peak value becamelow (-48dB) back in a normal condition.

Mitsubishi Heavy Industries Technical Review Vol. 57 No. 1 (March 2020)
6Figure 9 Example anomaly transmission device detected in motor-driven equipment
diagnostics|5. Conclusion
The maintenance of motor-driven rotating machinery used in various industrial applications
is mostly time-based. Therefore, even non-defective machines have often been maintained underexcessive quality control. In addition, a vibration meter is generally used to diagnose the conditionof rotating machinery, which requires the installation of sensors, cable work on site, etc., resulting
in increased cost. The high cost has been one of the factors delaying the introduction ofcondition-based maintenance.
In the developed MHPS-TOMONI® motor-driven equipment diagnostics service, theconditions of all rotating machinery are diagnosed through a simple system in which clamp-on
meter of current are installed on the power line for driving the motor, and the predicted diagnosis
values (of one year later) are also presented. Persons in charge of maintenance can expect thisservice to facilitate planning of the maintenance of motors and rotating machinery and reduce
excessive maintenance costs. We are going to collect various data on motor-driven equipment,
improve the prediction accuracy with machine learning and promote maintenance control inaccordance with equipment conditions with reducing unnecessary maintenance costs.
MHPS-TOMONI is a registered trademark of Mitsubishi Hitachi Power Systems, Ltd. in the United Statesand other countries.

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