3 phase motor

[jksmith82]

Hi All,
I have a 5 hp motor rated at 208-230 3 phase. The supply is 240v 3 phase. The spec sheet says the supply can be + or - 10%. If I remember correctly these motors are rated for 208 or 240. Am I correct? Have a good rest of the day.

Jim

 

[LarryFine]

The voltage rating is a range, not two specific ratings. I.e., 208v - 10% through 230v + 10%

The higher the voltage, the lower the current. The motor will love your 240v.

By the way, motors rated at 230v are designed to expect to receive 240v.

 

[Jraef]

The voltage rating is a range, not two specific ratings. I.e., 208v - 10% through 230v + 10%

The higher the voltage, the lower the current. The motor will love your 240v.

By the way, motors rated at 230v are designed to expect to receive 240v.

To expand a bit:

240V is the national standard for "Distribution Voltage" (ANSI C84.1); meaning what the utility is supposed to supply to the Service Entrance point. Distribution Votlage is required to be +-5% maximum, although some utilities strive for tighter control.

230V is the standard for "Utilization Voltage; meaning what the equipment is designed to use. Utilization Voltage is always lower because it is EXPECTED that there will be a drop in voltage from the SE point to where the equipment (in this case motor) is connected. NEMA requires +-10%, but in the case of 230V, motors are often designed as -15% in order to allow for a 208V source. That is typical for 5HP and under, but is NOT absolute, "your mileage may vary". Always check to be sure when using 208V systems.

 

[jksmith82]

Thank you both very much. The information was extremely helpful. Have a great evening.

Jim


Sent from my iPhone using Tapatalk

 

[retirede]

To expand a bit on what Jraef said, a motor designed for 208v supply will normally be nameplated 200v.
When a motor is labeled 208/230, it is basically a 230v design that may tolerate a 208v supply. It would not be unusual for such a motor to be rated at 1.15 service factor at design voltage, but only 1.0SF at 208.

 

[jksmith82]

Thanks for the info retirede.

Jim