The vast number of choices can make selecting a cord set a daunting task. But before selecting a cord set, it's critical to evaluate the environment and understand why a cord set is required. Understanding the need will help to narrow down the selection significantly.
Thirty years ago, there wasn't a choice. If you were involved in industrial automation, everything was hardwired. Most often, sensors and actuators came with long wires already attached or individual wires that weren't even jacketed together. Those wires would be threaded through conduits and then wired into the system. This was a time-consuming process that required the services of an electrician, costing organizations significant time and money.
Building the system is one thing, but servicing it is another. If a sensor or actuator needed to be replaced in a hardwired system, the entire device would need to be disconnected, removed and replaced, and then rewired. Again, this required an electrician. In addition, any machine downtime causing repairs like this was very costly.
M8 and M12 to the rescue
A system that is connected with M12 and M8 connectors makes assembling, testing and servicing an industrial control system faster and less expensive. While the upfront investment of cord sets and connectors is greater than cables and wires, the cost savings comes from a reduction in labor and maintenance costs. A large system that might take a week to hardwire could be wired with connectors in as little as two days. The savings accrued by reducing the installation time is significant, but now, wiring a connected system does not need to be done by an electrician, which adds to the savings and further justifies the higher price point for M8 and M12 connectors.
Another advantage: Start-up and testing of a machine is faster. A lot of time spent during start-up is the result of miswired devices. Prewired and tested cord sets eliminate the majority of wiring errors. Additional cost reductions come from reduced downtime, as cord sets can easily be replaced without the help of an electrician. Connected sensors and actuators can also be replaced without rewiring the system.
Choosing the right cord set
Like most engineering decisions, there's a balance between cost and performance. For instance, using an armored cable with stainless-steel coupling nuts for an application where cord sets are run in wire trays in a temperature- and humidity-controlled environment isn't the most effective solution.
First, list out the environmental needs of your application, and start with the lowest cost solution for your application. An unshielded cord set with a PVC jacket is typically the lowest cost option. If your application requires cable flexing, moving to PUR-jacketed cable is a good choice with only a slight price premium.
For example, in a high electrical or electronic noise environment, a shielded cable may be required to ensure communication reliability with sensors or actuators. If the equipment will be exposed regularly to water or will reside in a high humidity or salt spray environment, consider stainless-steel coupling nuts for the cord sets.
Each of these additional features described will increase the cost of the cord set, but that slight increase in price will help you avoid replacing the cord sets due to product failure—or worse, intermittent failure.
Although 30 years is a long time for any product to exist in the market, the M12 and M8 product families continue to be used in new designs every day. With the continual addition of new product features, these connectors will be around for a long time to come.