Jay Hendrix
Product Marketing Manager—Connected Power,
SolaHD, Emerson
A: Connectivity provides a window into your power supply’s health helping avoid unplanned disruptions and shutdowns. The connection to your power supply allows key diagnostic information to be communicated on the network to the control system. Along with diagnostics, key power-supply alarms alert operators when critical events are occurring. Insight into monitoring trends and responding to alarms enables operators and service technicians to anticipate maintenance needs, keeping your facility up and running.
Q: What about a power supply that has a DC OK contact; isn’t that good enough?
A: The DC OK relay contact is used to alert an operator that the power supply output power is good. The relay would open on a loss of dc power. This is useful for redundant operations or potentially in a safety shutdown sequence. However, at this point the dc power is already lost and any chance of identifying and catching an issue in advance is gone. This is an after-the-fact indication.
Q: Why is it important to monitor a 24 Vdc power supply? What can a smart power supply tell me?
A: In critical production processes within a facility, a power interruption or failure to a process controller could result in catastrophic loss. The slightest process variability could affect the complex reactions of multiple components, leading to substandard and unacceptable final product.
Using connected power supplies enables operations to monitor critical power parameters and key alarms, look for unbalanced loads and abnormal conditions and improve overall equipment effectiveness (OEE).
A connected power supply can provide real-time parameters such as input/output voltage and current, power-supply temperature, power-supply alarms and events and useful-life information.
Q: What are the factors that affect the life of a power supply?
A: How hard the power supply is stressed throughout its life affects its longevity. This will include the power-supply load and environmental temperature. Heavy load and high temperature are the factors that will shorten power supply life.
Q: How long should a typical power supply last?
A: Under normal circumstances a power supply will last 10 years, so how should you estimate the actual expected life of a power supply? Power supplies that support communication may be able to provide lifetime operating hours. This value can be compared to the power-supply specifications to gain insight into remaining life. Some power supplies may provide an indication of expected remaining useful life. This may be a percentage value that counts down over time or thresholds of life left. The countdown percentage is similar to the oil change indication in your car.
Q: What protocols are available for smart power supplies?
A: The typical industrial protocols are available in the market, depending on the supplier. Some of the common protocols that run on Ethernet are EtherNet/IP, EtherCAT, Profinet, and Modbus TCP. Highway-addressable-remote-transducer (HART) protocol is widely used in process automation and may be an excellent option. IO-Link is a short-distance point-to-point protocol. Some suppliers have adopted IO-Link for power-supply communication.
For more information, visit www.solahd.com.
