Well, of course power is importand in any technical installation. That goes without saying. Put there is power and there is power.
What and Why?
A device can be powered using a normal power outlet in the wall and use what is provided there. Here in Sweden, that would be 230V. We can also use other voltages like 5V, 12V, 19V, 24V, 48V, 54V and so on. If we need those we need something that transform power into these voltage levels.
We can also power our devices using PoE (Power over Ethernet). This means our network ports deliver power, spanning from a few watts to 90W depending on the device.
The quality of the received power can also differ depending on where we are. Either in some city with a stable power supply or far away with less reliable access to power or maybe access all the time but with variations in voltage. Unstable power delivery can cause all kinds of strange behavior in our systems.
In some switches this can happen for the simple reason that it reboots and when it comes online again, all PoE devices start at the same time drawing alot of power in the first second, more than the particular switch can deliver at that moment, resulting in issues with the products once they are online.
But How?
UPS
There are several different kind of products that will help us to monitor and handle power issues. One that probably come to mind for many of us is a UPS (Uninterruptible Power Supply), a battery simply put in front of the equipment that can’t be allowed to go offline. That paired with some kind of generator can help keep devices online as long as there is fuel for the generator.
But it’s a solution to just one problem. A power failure. Of course, if we don’t have power, other methods are pretty useless so lets start with the UPS.
PDU
The other device I will write about are PDUs (Power Distribution Unit). Device that will make sure each device will receive power. By putting a UPS to handle incoming power and then a PDU after it to make sure each product receives power, we are off to a good start. But if we leave it at that, we actually only built ourself an overly expensive power strip and we don’t want to stop there in our installations.
Now, an ethernet connected (or RS-232 for that matter) PDU will have a lot more possibilities. I have had a chance to test some different PDUs out and they can help us out alot with making sure our devices keep working.
My absolute favorit PDU so far is the GUDE 8291. It’s not the cheapest device out there but it has got some interesting features when it comes to different connectors and voltages.
First, it’s got four C13 connections for “normal” 230V (again, here in Sweden), each rated at 10A.
But a lot of PDUs have C13 or Schuko connectors so that’s not so special.
What it does have however is DC connectors to. It’s got four banks of different connectors.
Bank A is 5V with five individual connectors, each can be either a USB-A or a detachable screw terminal.
The other three banks, each with four connectors, can be set to either 12V or 24V.
In a rack installation, this can help us greatly by not having to have for example power adapters or individual 230V to USB 5V connectors taking up a lot of space in a traditional power strip. We can simply create a cleaner and more reliable rack installation.
Besides the connectors themselves, a PDU can give us a lot more functionality. Of course, feature sets will vary from manufacturer to manufacturer where some will have chosen to develop their own set of features. The functions I describe below are from different models of the GUDE line of products and are not a complete list of everything that the devices can do but a few examples that can be important in many ProAV (and other) installations.
First, COMMUNICATION. Since the device has an API (accessible over ethernet (network) or RS-232, we can communicate with it easily. Either by using the ready made modules GUDE provide like those for a Crestron system, or by sending our own commands and receive data that we can interpret ourselves.
There are also other methods of communication built in like MQTT, modbus, telnet and SSH.
Second, MONITORING. We need to make sure the device itself is online. This can be achieved by an external monitoring system like SNMP or Crestron XiO Cloud (there is a module for it in the platform). GUDE also support systems like Domotz and PRTG as well as external syslog servers and more.
Third, CONTROL. Each power outlet can be set to on or off using programming, making it possible to start and stop devices at will. Each power outlet can also be set to on, off or last state when the PDU starts up (for example after a power outage) and the outlets can be set to start in sequence so that not everything starts up at once, creating a spike that triggers the circuit breaker. This can be very useful if the device connected is something like an LED wall or similar that can draw a lt of power when it starts up.
Fourth, AUTOMATION. Another nice feature of these PDUs is that we can activate a “watchdog” for each outlet, telling the device that on outlet A3, there is a signage player with IP-address X.X.X.X. If it stops replying to Y number of ping request, power cycle that port. Repeat two times with Z minutes between and if the signage player still isn’t responding to pings, send an e-mail to AAA@BBB.CC.
This way, we can have the system self heal if there is a problem and we don’t have to go on site doing expensive and time consuming work for the end customer.
Fifth, SENSORS. In many racks and for example behind a LED wall, there may be a reason to measure temperature. The GUDE devices will allow you to add one or two sensors that can measure temperature, humidity and in some models, air pressure. This way we can make sure things aren’t overheating and if they are, we can add logic to the installation to notify us or to turn certain things off.
These are some of my thoughts on PDUs and the importance to have this often underestimated piece of equipment in our installations.
Disclaimer: This article is NOT a payed advertisement in cooperation with GUDE as a company nor is it written with their knowledge nor influence.