How To Read Motor Nameplate

How To Read Motor Nameplate - Every motor nameplate must show basic data such as voltage, Full Load Ampere (F.L.A), and frequency.

North America, Europe, Japan, Africa, has different standard. To know standard of motor is very important. It helps you from buying wrong motor. Yet, no each motor has specific data. Sometimes name plate did not show the diagram voltage, efficiency. Nevertheless, many motor always show voltage, full load ampere and frequency.

NEMA: National Electrical Manufacture Association
NEC: National Electrical Code
JIS: Japanese Industrial Standard
IEC: International Electrotechnical Commision

Case I

Manufacture: TECO, take a look at datasheet of TECO www.teco.com.tw/fa/ecatalogue_file/en/AEEFAEVFTA1001.pdf

Code: This code based on TECO's manufacture.

Output Power: 3.7 KW / 5 HP

Capacity of mechanic that produce from motor. NEMA always show power in HP and IEC always show power in KW. Sometimes manufacture show both of them. This nameplate did not show the efficiency, you could see manual book of your motor. For instance, this motor has 80% efficiency. So, the motor needs 100/80*3.700 Watt = 4.625 Watt. Total watt that used by motor is 3.700 Watt. Other 925 Watt is loss and became hot temperature, friction and etc.

Rated Voltage: 220V / 380V

If you have rated volts 220V, you have to set the starting system to delta and full load ampere is 13.87 A. If you have rated volts 380V, you have to set the starting system to star and full load ampere is 8.03 A. Many manufactures has dual-voltage or tri-voltage to make motor can be operated in other country. Every motor has tolerance, 5-10%. Let say in this case, TECO motor has 5% tolerance. So for 220 Volts, the voltage tolerance is 209-231. And 380 Volts is 361 V – 399 V.

NEMA allowed motor to be operated both under and over 10%. For instance, motor nameplate shows 230 Volts. Maximum under voltage is 207 Volts and maximum over voltage is 253 Volts.

Based on NEMA

NEMA gives manual, what happen if the voltage under or over occur.

This is graphic that will tell you the best what will happen if the voltage has variations.

Full Load Ampere

Full Load Ampere (FLA) is maximum current of motor. Yet, motor could be operated from their nominal current, but motor has time limit when the motor over current. The nameplate FLA usually is used to select the correct wire size, motor starter and also overload protection to protect the motor.

When motor start, the current will over current. If you want to know the time limit of your motor, you have to see motor curve datasheet.

Frequency Rate: 50 Hz

This motor only can be used in 50 Hz. It means International Electrotechnical Commision (IEC) standard. For National Electrical Manufactures Association (NEMA) is 60 Hz.

Revolution Per Minute: 1440 RPM

This is table of RPM, between frequency and poles.

Frequency	Number of Poles
	2	4	6	8	10	12	14	16	18
60-cycles	3600	1800	1200	900	720	600	514	450	400
50-cycles	3000	1500	1000	750	600	500	428	375	334

Formula for RPM, Ns = 120F / P

where,

Ns = Syncron rotation

F = Frequency

P = Poles

 

Poles: 4

Based on the table, we know that this motor has 4 poles. Because, this motor has 1440 RPM. There are slip for motor, so the RPM not exactly 1500, but 1440. Which 60 is slip. Here's figure about poles.

Maximum Ambient Temperature: 40 C

Ambient means the temperature of the air surrounding the motor. Normal motor has ambient temperature -15 C to 40 C.

Power Factor

Power factor that shows at nameplate is pf when motor has full load. Value of power factor depends on how much load that coupled with motor. More decrease of load, so do the power factor. Take a look at the figure.

Service Factor

According to NEMA definition is how much load and FLA could be operated over value of nameplate.

For instance,

10 HP with 1.25 SF. So, motor could be operated till 12.5 HP.

Altitude

NEMA’s standard has maximum elevation (3300 ft or 1000 meters). If over from the standard, motor have to be derived. Below is table of HP relation with altitude.

Altitude		1,0 SF	1,15 SF
Ft	Meters
3,300  – 9,000	1000 – 2700	93 %	100 %
9,000 – 9,900	2700 – 3000	91 %	98 %
9,900 – 13,200	3000 – 4000	86 %	92 %
13,200 – 16,500	4000 – 5000	75 %	85 %
> 16,500	> 5000	Call Manufacture

Case II

Description (click for large image):

More detail click here for brochure.

Note

Sometimes nameplate did not show the start motor. If do so, you should see at the cable connection. In many motor that has power below 1 Hp usually using delta connection to start motor.

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Here's other motor nameplate.