Back to Basics

Armed with your knowledge of starters, contactors, and overload relays, you are now prepared to help the customer. The two most fundamental questions you need to ask are:

Based on the answer to these two questions, you will be able to easily navigate through the various power control devices and accessories to narrow your selection.

Interviewing the Customer

When you are selecting a device to recommend to the customer, you will need to get a considerable amount of information about the customer’s application.

Consult the chart below for the type of device, and obtain customer data for each topic. Some sample responses are given to help the customer understand what you are asking about.

Contactor	AC Manual Starter	Motor Starter
Type of load (motor, lighting)Size (HP, amps)Motor voltage (230, 460)Enclosure type (NEMA 1, 12 etc.)Control voltageNumber of poles	Size (HP, amps)Motor Voltage (230, 460)Enclosure type (NEMA 1, 12 etc.)	Starter type (FVR, RVS)Horsepower (starter size or amperage)Motor voltage (230, 460)Common or separate controlIf separate, control voltage (24, 120)Enclosure typeNeeded accessoriesFull Load Amps of motor (for heater selection)

NEMA or IEC? Open or Enclosed?

Part of your recommendation to the customer will be choosing a NEMA or an IEC device. You will need to obtain the following information from the customer.

NEMA	IEC
Motor voltage (230, 460)Horsepower (5, 10)Phase (1, 3)Common or separate controlControl voltageFull Load Amps of motorStarter typeEnclosure type	Motor voltage (230, 460)Horsepower (5, 10)Phase (1, 3)Common or separate controlControl voltageFrequency of stopping/startingFull Load Amps of motorStarter typeEnclosure typeLife expectancy required

There may be other considerations, depending on the application. But, remember the general rule of thumb when dealing with IEC and NEMA: NEMA is simpler to apply, but more expensive. IEC satisfies specific applications, and is less expensive.

Checking the Motor Nameplate

The motor nameplate is a source of useful information. You can find the Full Load Current (FLC), the Motor Service Factor (SF), and the trip class (10 or 20) there.

In the case of overload heater coil selection for continuous duty motors, refer to the manufacturer’s tables, based on the motor’s nameplate FLC rating. The size of the heater coil is based on the FLC, the motor SF, and trip class.

Armed with the right information from the customer, you can make an informed recommendation to meet the customer’s needs.

Modifications

Often, a customer will ask if a contactor or motor starter can be modified. Generally, they are looking to change its functionality. The answer is yes, as long as the device does not require replacement.

Contactors and motor starters are easily modified by adding devices to expand their capabilities. The modifications that can be made are analogous to adding accessories to your car, like a CD-player. They change the performance of the control device to meet a specific need.

Some devices that are commonly added include: