Overview on Predictive Maintenance

Predictive Maintenance Model

Advantages of PdM

- Reduced unplanned downtime.
- Less time and resources required for troubleshooting.
- Less risk of catastrophic failure.
- Longer plant lifetime.
- Remote monitoring & support.
- Improved Plant Safety and Controlled Insurance Costs.

Predictive Maintenance Model

Industrial Process Machinery

PdM is applied on both electrical and mechanical machines. For electrical machines: motor, generators, circuit breakers.
For mechanical machines: gearboxes, pumps, fans, rollers, crushers, conveyors, compressors.

Sensing Instruments

Sensor / Monitoring device Type Measured Value
Potential transformer, Capacitive couplers Voltage
Current transformer Current
RTD, Thermocouple, IR sensor Temperature
Tachometer Speed
Flux sensor Flux
piezoelectric, strain gauge Pressure
accelerometer Vibration acceleration envelope
Circuit Breaker Monitor -Mechanism time
-Arc Duration time
-Contact interrupting duty
Insulation monitor Online Monitoring for medium  and low voltage motors

Data Logger / Processing Unit

Sensors are connected to either data logger or processing unit.

- Data logger: is a data collecting device, collect readings from several sensors attached with, save these readings in memory module until download them to computer to perform analysis.

- Processing Unit: collect readings from attached sensors just like data logger and perform analysis and output, data  and analysis results are downloaded to computer to display results, trends and provide expert advice.

 
Ideal Model / Setting Values

- Ideal Model provide reference & threshold values of measured values to indicate the status of the machine.

- Ideal Model is done by either Processing Unit or Computer.

- Ideal Model is built by using sensor readings of healthy  machine or by entering the reference & threshold values by user.

 
Communication Media

Communication Media is used in data transfer between Data Logger or Processing Unit & computer. Communication can be established by:

- Serial link:        RS-232,RS-485.

- Wireless link:   GSM, RF.

- Power line:       by using modulator/demodulator to send sensor readings over power lines.

 
Server

- Maintains database of analysis results, trends, machine conditions.

- Communicates with Clients.

- Remote access for expert support.

 
Local Area Network / Wide Area Network

Client Computer can communicate with Server computers:

- Locally by using LAN.

- Remotely (Dial-up, Internet) by using WAN.

 
Client Computers

- Access Server Computer over plant-wide network.

- Operator Interface graphically depicts machine status.

- Engineering analysis functions.

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