Electrical FAQ

What You Need To Know About Electrical Equipment

As the specialists in electrical products and solutions, OTP has the answers you seek to enhance the performance of your industrial control, automation and electrical distribution. Below are answers to frequently asked questions. If you need more information, simply contact our knowledgeable staff today.

Q: I need to replace an AC motor on my line. What information do I need to supply my distributor?

A: To ensure the right product, be ready to share the following information: application, environment, horsepower, RPM, voltage, NEMA motor frame size, enclosure (TEFC, ODP), duty (inverter duty, speed range if inverter duty, across the line starting).

Q: My NEMA motor frame size has a YZ at the end, but I can’t find it in any of my catalogs. What does the YZ mean?

A: In a NEMA motor frame designation, the letters after the frame number have meaning. As an example, in 56C, the C designates a C-face on the motor. In your case, the Y is NEMA’s designation for NON-NEMA mounting and the Z designation is for NON-NEMA shaft dimensions. (NON-NEMA means dimensions outside the parameters of the motor dimensions set by NEMA for a given motor frame size).

Q: I think my AC motor is running hot. I can barely touch it. Should I be concerned?

A: A motor dissipates its heat through the skin of its body. Many motors will feel hot to the touch, but they are running well within their temperature range. As a first measure, review the location around the motor to make sure there are no obstructions that prevent airflow.

Another good step to take: measure the current on each leg of the motor leads. You want to make sure that the amperage of each leg is within the motor nameplate information. If the measured current is higher than the nameplate amperage, you may have an overloaded machine or an unbalanced voltage supply to the motor.

Q: Can I run more than one motor on one AC motor drive?

A: In most cases the answer is yes, as long as the combined total current of the motors do not exceed the amperage rating of the motor drive. A note of caution, however, if there are multiple motors on the same drive, you cannot provide over-current for either motor by itself. The overloads will not react unless the total current of both motors exceeds the drive rating.

Q: On my bottle line, I need to make sure that the caps are on all of the bottles. How can I do this?

A: Depending on the cap material, either a proximity sensor or capacitive sensor can be placed above the bottles as the pass-by. If a cap is missing, the sensor would send a signal to a relay. This would trigger the nonconforming bottle to be removed from the line.

Q: I’m building an operator station for my machine. My incoming voltage at the machine is 460VAC and all of my devices (PLC, pilot lights, pushbuttons) are 24VDC. What do I need to do?

A: Add a 480VAC to 24VDC power supply to the system to supply the needed lower voltage for the operator devices.

Q: What do the different NEMA designations mean for an enclosure?

A: NEMA 1: The Enclosure has vents in its body to allow air from the outside to enter and aid in the cooling of the components inside of the enclosure. These should be used only in very clean environments.

NEMA 3: Provides a degree of protection against falling dirt, rain, sleet, snow and windblown dust; will also be undamaged by the external formation of ice on the enclosure.

NEMA 3R: Same as NEMA 3, excluding protection against windblown dust.

NEMA 4: Watertight and dust tight; able to withstand jets of water; typically available with corrosion proof paint or stainless steel construction.

NEMA 4X: Same as NEMA 4, including protection against corrosion.

NEMA 7/9: Enclosures for explosion-proof atmospheres.

NEMA 12: Dust tight construction.