Data-driven visibility helps protect industrial processes and motors.
Industrial producers typically invest millions in their infrastructure. Despite such investments, many production facilities lack critical motor performance monitoring and reporting capabilities to help maximize efficiency and energy use and better manage overall operating costs.
Without the kind of data provided by integrated automation, producers are similar to a race car driver in a 200-mile-per-hour race who is just using a common automobile dashboard's fuel, speed and temperature gauges. Limited visibility into the performance of their production processes—and therefore how to optimize them—is only part of the challenge that producers face. If a process breaks down and production stops, costs of lost output and standby labor can mount by the hour.
Motors Are the Muscle
Electric motors are the muscle that keeps materials and work in progress in industrial processes. When a motor fault occurs, production can come to a halt until the cause is diagnosed and repaired and the motor restarted. These outcomes can put production at risk—ranging from reasonable (restart within seconds) to costly (restart taking hours or days).
Risk Insurance
Overload relays were invented to protect industrial motors from damages caused by overload conditions. They are specialized devices that can sense an overload or other adverse circuit condition, open a circuit and then provide control or some operational indicator. In effect, the motor protective function of a conventional overload relay can place process productivity at risk by protecting its connected motor.
Different overload relay types are available, ranging from simple thermal sensing units to more complex, solid-state relays. These may include a wide range of programmed intelligence and reporting capabilities, which is called smart motor management (SMM). An important feature of this type of SMM device is the capability of assuming local control of the process if communication is lost. While overload relays are designed to protect the motor only, SMM can help protect the motor and the process it drives.
Weak Link in Complex Processes
In the past few decades, industrial processes have become increasingly complex. Fast-changing market demands, including customer expectations of more diverse products (and mass customization of those products), require tremendous production flexibility from manufacturers. Competition among manufacturers drive them to respond.
Given this complexity and the demands for manufacturing flexibility and responsiveness, industrial engineers face the challenge to keep up. No matter how sophisticated their process and control designs, simple or catastrophic motor failure anywhere along the line can stop feeder, production or collateral processes with many possible consequences.
Smart Motor Management
Traditional motor starters, controlled by a PLC or DCS, provide little status and diagnostic data into the connected control system. For years, a single, contactor-operated auxiliary contact (ON status) and an overload-relay-operated auxiliary contact (FAULT status) wired to PLC or DCS inputs provided acceptable levels of status and diagnostic data.
A cost is associated with each input status and output control in a conventional PLC or DCS control system. In addition, a cost and complexity to wire is associated with the conventional two inputs and one output of the traditional motor starters.
In fact, the total cost of wiring 25 motor starters to their PLC or DCS alone (figuring an average of 100 feet of wire for each connection) can be up to $15,000, not counting conduit, cable tray or I/O cabinet space. Nor does it account for the difficulty in troubleshooting about 2.5 miles of wire if something goes wrong.
Clearly, another approach is needed. smart motor management. With an SMM device in place, all this information can be brought into the PLC or DCS without additional traditional I/O or interconnecting wiring, saving thousands.
Simply defined, this SMM model uses the latest in compact, solid-state technology configured with modular, pre-configured intelligence to provide a wide range of real-time operational data that can be used for early warning and post-fault diagnostics.
The configurable nature of SMM devices allows the user to select the device response to conditions that would cause other motor overload relays to trip.
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Figure 1. Optional measurements are also available with SMM.
Network or Local Control
If network communications fail, the intelligent overload relay can immediately take over local control of the motor until the network comes back up, keeping the process motors moving. When network operation returns, the local operating data updates the central control unit, so its operating profile stays current. In addition to predefined motor control applications, user defined logic elements, such as truth tables, timers, counters, etc. are included to allow the user to customize the predefined motor control applications to meet their individual needs.
Using PROFIBUS communications, these intelligent overload relays can provide much more operational data and information, such as:
- Load status (on, off, warning, trip)
- Warning and trip indicators (jam, loss of load, vibration and more)
- Statistical data (starts, trips, operating hours)
- Measured values (current, voltage, power factor, KW, temperature and more)
PROFIBUS DP can also save the cost and hassle of conventional wiring: up to 124 devices can be connected to a single two-wire network connection. These savings can add up fast and help offset, if not pay for, a plant's conversion to SMM. At the very least, the savings can accelerate the plant's ability to break even on its investment.
Power measurements such as the ones listed in Figure 1 can help plant management monitor site power consumption much more precisely and shed loads down to a single motor, which can help reduce peak usage charges. This information can also help them compare measured energy usage with utility billings to check for possible over-charges and get reimbursed. In effect, all the additional data that can be used to open a “window of visibility” for optimizing a plant's motor infrastructure becomes available.
Applications
SMM, has many uses in industrial processes, whether the processes feed production, make up production or dispose of production wastes.
Pumps & Mixers
Fluids can be part of industrial production as work-in-progress gets washed, cooled, coated, rinsed or any combination, with excess fluids re-circulated or disposed. In
