Two practices that persist in many plants are point-to-point hard wiring and running separate cables for power and control wiring. Newer hybrid connector technologies, however, make it possible to eliminate both of these practices.
Multipurpose hybrid connectors like the one shown in Fig. 1 allow the use of preassembled composite cables with bundled lines carrying electrical power, control signals, data communications, even air for pneumatic devices.
Fig. 1. Examples of HARTING multipurpose hybrid connectors for pre-assembled cabling (click to enlarge)
Design for maintenance
The design-for-maintenance mantra frequently goes unheard when it comes to wiring practices. One reason may be the perception that connectors are going to add a lot of cost to the wiring. However, studies by HARTING, Inc. of North America reveal that the connector cost premium at the front end can easily be offset by lower installation and maintenance costs. This can be particularly important in factory-automation projects, which often involve complex equipment and installations.
HARTING’s time and cost studies found that projects involving several pieces of equipment benefited most from connectorization. In one such project, the OEM found there could be a 40-50% cost premium over hard wiring in system production. Conversely, when calculated for disconnecting several pieces of equipment for shipment and reconnecting at the plant site, the total cost for connectorized wiring turned out to be about 50% less. These gains resulted from shorter installation time, fewer wiring errors, less debugging time and simpler plug-and-play startup.
Clearly, connectorization is easiest to accomplish on new installations and plant-equipment upgrades. Difficult maintenance and repair problems, however, often call for extensive disconnections in hard wiring to troubleshoot existing equipment. These types of difficulties can make the retrofitting of new cable and connector assemblies cost-effective.
In addition to hybrid assemblies, connector manufacturers have become quite inventive in designing connectors that reduce overall wiring costs. For example, a recent machining transfer line project involved 480VAC (AWG 10 power wiring) and control signals (AWG 16 wires) for a large number of drive motors along the line. The basic design choices were (a) hard-wire separate power and control lines to the motors through a single cable; (b) wire with separate connectorized power and control cables; or (c) make up composite AWG 10/AWG16 cable assemblies with connectors. HARTING was able to supply a hybrid “T” connector for the cable drops to the motors (Fig. 2). The machining line was assembled in modules, shipped to the site, installed and wiring was simply plugged together. Overall costs were substantially lower than using point-to-point hard wiring.
HARTING, Inc. of North America