This project was the result of a discussion with the staff of a dairy processing factory about updating motor equipment, specifically upgrading from simple hardwired input/output (I/O) motor monitoring to include more diagnostic information.
The factory is a significant diary site processing over one million litres of milk per day into various cheese products. No specifications were provided for the project, simply an overall aim to update existing equipment and increase efficiency and safety through better monitoring and managing of motor performance.
Intelligent motor starters for a Motor Control Centre (MCC) upgrade with integrated motor control and monitoring were suggested and decided on. After detailed planning, the client approved the development of the suggested MCC.
The system uses motor starters interfaced to the system programmable logic controller (PLC) for real-time motor control and to generate real-time performance data. The PLC and supervisory control and data acquisition (SCADA) software (CitectSCADA) collects and analyses this data, then presents it to operations staff.
Monitoring includes motor starter ready, energised feedback, fault warning, trip causes and average motor current. This is displayed as motor status for each motor. In addition, some motor starters are integrated into the safety system through the PLC’s safety functions and continuously monitored emergency stop push buttons and gate switches mounted on production equipment.
The MCC includes the following elements:
- Hardwired I/O motor control replaced with Schneider TeSys U compact motor starters with integrated communications
- Allen Bradley PLC connects to each motor starter through Ethernet industrial protocol (Ethernet/IP) to Modbus RTU gateways for status monitoring
- PLC hardwired outputs are used to control motor start/stop (including reversing) to ensure safe functioning
- PLC connection to the Schneider Altivar variable speed drives using the Ethernet/IP protocol for full drive control, monitoring and diagnostics
- Allen Bradley 1734 series Point Guard input/output safety modules evaluate dual-channel consistency between two input signals and provide redundant control by using two output signals to allow implementation of safety Category 3.
The project was completed within budget in a period of five weeks. Software testing and type testing of the communications networks were conducted prior to installation, to ensure the system would function correctly.
As requested by the client the system was installed during the factory’s existing shutdown period. This compressed timeline required thorough planning and time management. In addition to design, installation and testing, Pesce produced manuals on the system and trained the client’s staff to operate and maintain it.
