aes92000
Member
- Location
- Katy, Texas
QUESTION
92. Determine the MAXIMUMsize overload protection required for a 480-volt, 3-phase, 15 hp,continuous-duty ac motor, where given the following related information. Assumethe value you select will permit the overload device to carry the motor loadand modification of this value is not required.
* Design C
* temperature rise - 40 deg.C
* service factor - 1.12
* nameplate ampere rating -18 amperes
A. 20.7 amperes
B. 18.0 amperes
C. 22.5 amperes
D. 23.4 amperes
ANSWER
92. A -For general motor applications, in compliance withSection 430.6(A)(2), the
ampere rating provided on the motor nameplate is used tosize the overload
protective devices intended to protect the motor. Section430.32(A)(1)
indicates where the motor has a service factor of lessthan 1.15, the rating or
setting of the overload protective device is to be notmore than the motors
nameplate ampere rating:
Motor nameplate FLA = 18 amperes x 115% = 20.7 amperes
according to Section 430.32(A)(1), I used the nameplate 18A with 40C at 125% to reach my answer of 22.5
92. Determine the MAXIMUMsize overload protection required for a 480-volt, 3-phase, 15 hp,continuous-duty ac motor, where given the following related information. Assumethe value you select will permit the overload device to carry the motor loadand modification of this value is not required.
* Design C
* temperature rise - 40 deg.C
* service factor - 1.12
* nameplate ampere rating -18 amperes
A. 20.7 amperes
B. 18.0 amperes
C. 22.5 amperes
D. 23.4 amperes
ANSWER
92. A -For general motor applications, in compliance withSection 430.6(A)(2), the
ampere rating provided on the motor nameplate is used tosize the overload
protective devices intended to protect the motor. Section430.32(A)(1)
indicates where the motor has a service factor of lessthan 1.15, the rating or
setting of the overload protective device is to be notmore than the motors
nameplate ampere rating:
Motor nameplate FLA = 18 amperes x 115% = 20.7 amperes
according to Section 430.32(A)(1), I used the nameplate 18A with 40C at 125% to reach my answer of 22.5