For most of the country, the fall season brings on the cooler weather. This last summer saw many areas of the country with record high temperatures over an extended period of time. Often the result of this condition is that local power companies cannot supply the power demand and the supply voltage is lowered.
In very basic terms when the supply voltage drops down, the current demand goes up. This is because the device being supplied has a power demand that must be satisfied. Power is the product of voltage and current. Higher current results in heat and temperature rise.

A brown out is a partial loss of power, an under voltage condition, as opposed to a black out which is a complete loss of power. A surge is an over voltage condition that can last several seconds and is usually more than 20% higher than normal. A voltage spike is a brief, split second, condition of extreme over voltage often due to the in-rush of current to an inductive load; as with an electric motor turning on or off on the same line. Spikes are also often the result of local lightning strikes. Noise is a catchall word that includes spikes, brownouts and any aberrations on a supply voltage line.

What does this mean to the board shop? Components in computers are rated with maximum current values. If these values are exceeded, the chips actually burn out, causing a computer failure. Conversely, when the voltage goes up, problems can be seen as well. Motors and valves run hotter and risk being burned out. If these conditions do not cause a failure in the system, they certainly can shorten the life of the unit. Noise on the line frequently can cause erroneous signals that will change the condition of a device and throw off the logic in a controller. This can cause a malfunction that defies explanation.

As in life, we are faced with either too much or too little.
In order to minimize any potential problems, Multiline provides a Line Conditioner on our major systems; the Optiline PL, and X-ray Tooling & Inspection machines. The Line Conditioner regulates the incoming voltage level to some tolerance, usually better than +/- 10%, to prevent damage to the computer from brown outs and surges. It also filters out electrical noise and spikes. A similar, but smaller unit can be supplied with the Stacker/Interleaver and DePinner systems to protect the programmable logic units included. Commercially available units can help protect equipment that plug into wall outlets.

On the newest products, which incorporate Windows NT® operating systems, Multiline has included an Uninterruptible Power Supply, “UPS”. The main function of this device is to prevent the computer from crashing in the event of a voltage drop. Working with the machine’s computer, the UPS switches to battery power if the voltage drops below an acceptable level to give the software time to shut down properly.

The installation environment is specified for all of Multiline”s computer controlled systems. These specs are typical for computer control machines found in circuit board shops. Incoming power should be on a dedicated line, with a maximum of +/- 5% voltage fluctuation. Earth ground is also required. The elimination of all possible sources of electrical noise from the incoming power line is critical for the successful installation of any computer-controlled equipment.

All of these environmental specifications, and other important installation requirements, are called out on the machine’s Footprint Drawing.

It is up to Plant/Factory Engineering to understand the nature of the power being supplied to the shop floor. There are chart recorders available that will monitor incoming voltage over a time period so that a Plant Engineer can understand what is available to him. Local power companies will consult with the factory on particular problems or needs. Multiline Technical Service can often help, however, these problems are usually solved by the local utility company working with local electricians familiar with local power conditioning problems.

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