Improving power supply intelligence

Control cabinet power supplies and uninterruptible power supplies (UPSs), thanks to higher-level intelligence, are evolving to provide operational information to users to make operations safer and more efficient.

By Ken Allwine June 7, 2019

Control cabinets are evolving at a rapid pace to include more functionality, higher-level intelligence and expanded communications. With the increasing adoption of the Industrial Internet of Things (IIoT), system owners have more data available than ever. Control cabinet power supplies and uninterruptible power supplies (UPSs) are evolving to provide operational information such as voltage, current, health, temperature and other data points.

While industrial networks have existed for many years, there were limitations in their structure, scalability and throughput until recently. The industrial networking community made many technological and security advances in the last decade, which helped minimize these earlier concerns. Users now have the capability to send massive amounts of data almost anywhere.

Historically, when we look at the power structure inside a control cabinet, it only has been given enough thought to get the right voltage and the appropriate amount of current for the application. On occasion, if the circumstances required it, a battery back-up solution would be added. Over time, however, this thought process has changed. Technology and the capability of power supplies have increased, giving system integrators and end users more options. The low-voltage segment of the cabinet now has become an area of more scrutiny in higher-level applications, including the battery back-up options.

Just as more information has become available with sensors, drives, safety and other devices, more information is available from the low-voltage segment of the control cabinet. For many years, power supplies only had an LED indication showing it was “on.” Some power supplies also included a “DC OK” contact. Today, the latest generation of power supply and UPS technologies are emerging with interfaces with more capability.

Why get power supply data?

The power supply is the heart of a control cabinet. Without quality power, the components within the cabinet can be unreliable. With more points of data available from a power supply, the system owner has better insight into system performance. Once turned on, a power supply is rarely turned off. If the facility operators know the operating hours of the power supply, they can better plan preventive maintenance on equipment.

Loads change over the operational lifespan of a power supply in a control cabinet. The first reason for load change is the age of the loads. As they age, many loads become more resistive. This causes a slow, but increasing level of current draw. The second reason is system expansion. When the number of input/output (I/O) connections increase, operators might not always account for the overall load on a power supply. In both situations, the increased demand can have adverse and potentially severe consequences on the power supply. A 4-20 mA output providing real-time current level information can be sent to an analog input on a controller providing feedback information. This data could be used to provide a threshold warning to maintenance personnel.

Information highlighted in the previous examples is becoming increasingly present on power supplies. This may take the form of discrete I/O on the power supply itself. Network interfaces, such as IO-Link device network and EtherNet/IP Ethernet network, also are starting to show up on power supplies. Battery back-up solutions also lend themselves very well for remote connectivity due to their function in the control cabinet.

UPS remote condition monitoring

Batteries are the weakest point in UPS systems. The condition of the UPS battery determines if the UPS can exercise its function or not. Remote condition monitoring can give the maintenance team accurate data about when a battery needs to be replaced. This can reduce preventive maintenance costs. If batteries are replaced too soon, the owner is wasting money on equipment that is still good. If the batteries are replaced too late, the UPS cannot serve its function of reliable back-up power.

Remote indication from the UPS provides valuable insight into the real-time condition of the low-voltage power system in a control cabinet. These UPS systems now are available with direct industrial network connection through protocols such as EtherNet/IP, Modbus TCP/IP, Profinet and EtherCAT. Other interfaces such as USB and RS-232 are available for local PC connection and information exchange. Information such as battery health, battery state of charge, temperature, voltage, remaining life, remaining buffer time and output current provide the user important information regarding the state of power-system health.

As control systems continue evolving, so will power supplies, UPS systems and associated products. IIoT proliferation will continue, and the low-voltage power system will be able to provide the information system owners seek.

Ken Allwine is associate product marketing manager, Phoenix Contact USA. Edited by Chris Vavra, production editor, Control Engineering, CFE Media,


Keywords: UPS, uninterruptible power supply, cabinet power

Control cabinet power supplies and uninterruptible power supplies (UPSs) can provide critical operational information to users.

Without quality power, the data from a UPS is unreliable.

Remote monitoring systems can help users learn when something is about to fail in a UPS.

Consider this

What is the most important piece of operational information from your UPS?

Author Bio: Ken Allwine is associate product marketing manager, Phoenix Contact USA