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A reduced voltage starter that is perfectly suited to one application may be totally inappropriate for another.
You will need to obtain the following application information from the customer:
- Motor nameplate full load amps, locked rotor amps, horsepower rating, and (if available) motor torque/speed curve
These (and the motor load requirements) are the most important factors in determining the size of the starter required.
- Starting and stopping requirements
Longer start and stop times will allow for smoother starts and stops.
A pulse start and/or a jog option may be useful for applications such as dough mixers, coal handlers, or plastic extruders.
Some customers don’t require a smooth stop. For others, it’s a necessity. A pump application will require a soft stop to prevent damage from water hammer. A conveyor application may require a soft stop to prevent product from being damaged.
- Torque requirements of the driven machinery and the load inertia
- Number of starts required per hour
This is necessary because there could be an issue with heat dissipation if the number of starts per hour is excessively high. If applicable, this figure should include the number of times in a typical hour that jogging may be required.
- Overload protection required
Remember that starters all offer overload protection, which is gauged on Class. A Class 10 starter will trip if current draw is 6 times the motor’s full load amps for more than 10 continuous seconds. Likewise, a Class 20 starter will trip in 20 seconds.
- Electrical service range
Find out the customer’s electrical needs and match them in the product catalog. Is the customer running 480-volt, 240-volt, or some other line voltage?
- Inrush limitations imposed by the utility
- Cost limitations
- Environmental Concerns
Talk with the customer about the application environment. Solid state starters can be hampered in harsh environments, such as extreme heat. An enclosure and/or special cooling system may be required for such an environment.
- Enclosure type required
Enclosures provide protection for both the operator and the equipment. The customer has a number of options available. Work with the customer to determine which enclosure type is appropriate to the application.
NEMA 1 – General Purpose. This enclosure type is for general purpose, indoor use. It is suitable for most applications where unusual service conditions do not exist. It provides protection from accidental contact with enclosed equipment.
NEMA 12 – Dusttight. This enclosure type is for indoor use. It provides protection from dripping non-corrosive liquids, falling dirt, and dust.
NEMA 3R – Raintight. This enclosure type is intended for outdoor use. It provides protection against falling rain and sleet, and damage from external ice formation. It has a gasketed cover.
NEMA 4 – Watertight. This enclosure type is intended for indoor or outdoor use. It provides protection from splashing or hose-directed water, wind-blown dust or rain, and damage from external ice formation.
NEMA 4X – Corrosion Resistant. This enclosure type is intended for indoor or outdoor use, where corrosion resistance is required. It is constructed of stainless steel, polymeric, or fiberglass. It also provides protection from splashing or hose-directed water, wind-blown dust or rain, and damage from external ice formation.
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