In industrial automation we put our products through a lot. Extreme temperatures, harsh environments, and the demands of high performance can put a strain on the components of any machine. This led me to wonder, if our products could talk, what would they say?
Cordset: Cables have certain limpness which makes installing the cordset in automation easier to fit in tight spaces. Most cable installers prefer to have the least amount of slack in cable to prevent the cable being snagged or pulled during operations. Cables need to have a bend radius to prevent kinking of the conductors and a continuous flow of power. The bend radius is “the smallest radius of curvature into which a material can be bent without damage” (McGraw-Hill Dictionary of Architecture and Construction). Typically in a fixed (stationary) application, an unshielded sensor cable has a minimum bending radius of 8 times the outer diameter of the cable.
Power Supply: Everyone wants a friend. When a load is too much for one power supply, adding another power supply helps increase the voltage or current output. “The simplest method to create higher current is to connect the power supplies in parallel and leave only one supply in constant voltage mode. Some power supplies are equipped with analog control signals that allow auto-parallel or auto-tracking, a more elegant way to control multiple power supplies. Auto-parallel supplies can be controlled with a single master supply; a second advantage is that all of the master power supplies features can be used.” (Keysight Technologies) By stringing together power supplies, it allows more voltage or current but also keeps operations up and running.
Environments with debris and caustic agents, wear down equipment exponentially. When a cell goes down, every minute counts to get production up and running. An accessory like a cordset is important for operations, and can frustrate technicians when it fails. Cordsets do not last forever in this environment and to help save money, time and work, we came up with the concept of a “sacrificial cable.” The basic idea is to install a double-ended cable under 2 meters to help in situations where cables are placed in surroundings which will destroy the cable. A sacrificial cable’s main function is to save time reducing cable replacement downtime and money.
Sacrifice Cordset Solution: Used in extremely rugged applications to reduce cordset replacement downtime
A sacrificial cable does not have to be a specialty cable with a custom jacket; it could just be a 1 meter PVC cable that will get changed out often. The idea is that by placing a sacrificial cable in a problematic area and connecting it to a longer length cable this will allow maintenance to have a shorter down time when changing out failures less. This is accomplished with travel around the cell following a cable run and less maintenance expense in labor.
It’s another day at the plant, and the “Underside Clamp Retracted” sensor on Station 29, Op 30 is acting up again. Seems to be intermittently functioning…the operator says that the line is stopping due to “Error: Underside Clamp Not Retracted”.
You think to yourself, “Didn’t we just replace that prox last week?” A quick check of the maintenance log confirms it: that prox was indeed replaced last week. In fact, that particular prox has been replaced seven times in the last six months. Hmm….the frequency of replacement looks like it’s going up…four of the seven replacements were performed in the last two months.
What’s going on here? Is it really possible that seven defective proxes just all happened to end up at Station 29, Op 30, Underside Clamp Retract? Not likely!
As many machine builders, OEMs, individual plants, and large corporations decide to move from the “bus” to the “net” (Profibus or DeviceNet to Profinet or EtherNet/IP) they have a chance to look at all the new architectures available and decide on which is the best for them. Here are the first two topics to take into consideration:
Typical IP67 network topologies involve stand-alone I/O modules, providing 8 to 16 points of I/O per module. In some applications multiple stand-alone modules could be mounted within inches of each other. Thus was introduced the IP67 Network I/O Island, a modular IP67 I/O solution that allowed 8 to 60 plus I/O points to be connected to only one network node. This solution provided initial costs savings by reducing the number of network nodes used in an application, but brought along some new problems. One problem involved exceeding long sensor /actuator cordsets, with a centralized I/O solution remote sensors needed cordsets of 5, 10, or even 15 plus meters in length. The second issue was cordset management; imagine tracing a suspect cordset to the network I/O island with 60 plus connectors hanging off of the front of the unit.