York 00497VIP manual Wire Sizing, Voltage Source Figure

There can be electrical circuitry that presents an electrocution hazard. Be sure that the sources of all power supplies have been properly isolated and secured before attempting any service related activities.

External wiring, unless specified as an optional connection in the manu- facturer’s product line, is not to be connected inside the OptiView Remote Control Center cabinet. Devices such as relays, switches, transducers and controls may not be installed inside the OptiView Remote Control Center. No external wiring is allowed to be run through the OptiView Remote Control Center. All wiring must be in accordance with YORK’s published specifications and must be performed only by qualified YORK personnel. YORK will not be responsible for damages/problems resulting from improper connections to the controls or application of improper control signals. Failure to follow this will void the manufacturer’s warranty and cause serious damage to property or injury to persons.

PROPER INSTALLATION PRACTICES

Earlier relay systems were virtually immune to radio frequency interference (RFI), electromagnetic interfer- ence (EMI), and ground loop currents. Installation consisted of hooking up the point-to-point wiring and sizing the wire properly.

In an electronic system, improper installation will cause problems that outweigh the benefits of electronic control. Electronic equipment is susceptible to RFI, EMI, and ground loop currents which can cause equip- ment shutdowns, processor memory and program loss, erratic behavior, and false readings. Manufacturers of industrial electronic equipment take into consideration the effects of RFI, EMI, and ground loop currents and incorporate protection of the electronics in their designs. These manufacturers require that certain installation precautions be taken to protect the electronics from these effects. All electronic equipment must be viewed

FORM 50.40-OM2

as sensitive instrumentation and therefore requires careful attention to proper installation procedures.

There are a few basics, that if followed, will result in a trouble-free installation. The National Electric Code (N.E.C.) is a guideline for safe wiring practices, but it does not deal with procedures used for electronic control installation. Use the following procedures for electronic equipment installation. These procedures are to be used in conjunction with the N.E.C.

Wire Sizing 2

Size supply wires one size larger than required for amperage draw to reduce instantaneous voltage dips caused by large loads such as heaters, contactors and solenoids. Sudden dips in voltage can cause the processor to momentarily malfunction or cause a complete reset of the control system. If the wire is loaded to its maximum capacity, the voltage dips are much larger, and the potential for a malfunction is very high. If the wire is sized one size larger than required, the voltage dips are smaller than in a fully loaded supply wire, and the potential for malfunction is much lower.

The NEC code requires specific wire sizes to be used based on current draw. An example would be to use #14 gauge wire for circuits up to 15 amp or #12 gauge wire for circuits of up to 20 amp. Therefore, when connecting the power feed circuit to an electronic industrial control, use #12 gauge wire for a maximum current draw of 15 amp and #10 wire for a maximum current draw of 20 amp.

Voltage Source (Figure 3)

Selecting the voltage source is extremely important for proper operation of electronic equipment in an industrial environment. Standard procedure for electronic instrumentation is to provide a “clean” separate source voltage in order to prevent EMI, from other equipment in the plant, from interfering with the operation of the electronic equipment. Connecting electronic equipment to a breaker panel (also known as lighting panels and fuse panels) subjects the electronic equipment to noise generated by other devices con- nected to the breaker panel. This noise is known as electromagnetic interference (EMI). EMI flows on the wires that are common to a circuit. EMI cannot travel easily through transformers and therefore can be isolated from selected circuits. Use a control transformer to isolate the electronic control panel from other equipment in the plant that generate EMI.

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