1. You are working as a plant electrician. It is your job to install a 300-hp three-phase squirrel-cage induction motor. The supply voltage is 480 V. The power company has determined that the maximum amount of starting current that can be permitted by any motor in the plant is 3000 A. The motor nameplate is as follows: Phase: 3 FLA: 352 Volts: 480 RPM: 1755 Frame: XXX Code: L Will it be possible to start this motor across the line, or will it be necessary to use a reduced-voltage starter to reduce starting current?

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(Practical Application) #1 ) you are working as a plant electrician. It is your job to install a 300 hp three phase squirrel cage induction motor. The supply voltage is 480 V. The power company has determined that the maximum amount of starting current that can be permitted by any motor in the plant is 3000 A. The motor nameplate is as follows(photo) . Will it be possible to start this motor across the line, or will it be necessary to use a reduced voltage starter to reduce starting current?
### Practical Applications

1. **Scenario:**
   You are working as a plant electrician. It is your job to install a 300-hp three-phase squirrel-cage induction motor. The supply voltage is 480 V. The power company has determined that the maximum amount of starting current that can be permitted by any motor in the plant is 3000 A. The motor nameplate is as follows:

   - **Phase:** 3
   - **Volts:** 480
   - **Frame:** XXX
   - **F.L.A.:** 352
   - **RPM:** 1755
   - **Code:** L

   **Question:** Will it be possible to start this motor across the line, or will it be necessary to use a reduced-voltage starter to reduce starting current? 

### Analysis

To determine if you need a reduced-voltage starter, you need to compare the starting current of the motor with the maximum permitted starting current (3000 A). Typically, the starting current for a motor is 5-7 times the full-load current (F.L.A.). 

Given the motor's full-load current (F.L.A.) is 352 A:
   - **Estimated Starting Current Range:**
     - Lower Estimate: \( 352 \, \text{A} \times 5 = 1760 \, \text{A} \)
     - Higher Estimate: \( 352 \, \text{A} \times 7 = 2464 \, \text{A} \)
   
Since both estimates (1760 A to 2464 A) are below the allowable maximum starting current of 3000 A, it is likely possible to start the motor across the line without needing a reduced-voltage starter.

However, it is always recommended to further assess based on detailed motor specifications and practical testing to ensure compliance with all safety and operational standards.
Transcribed Image Text:### Practical Applications 1. **Scenario:** You are working as a plant electrician. It is your job to install a 300-hp three-phase squirrel-cage induction motor. The supply voltage is 480 V. The power company has determined that the maximum amount of starting current that can be permitted by any motor in the plant is 3000 A. The motor nameplate is as follows: - **Phase:** 3 - **Volts:** 480 - **Frame:** XXX - **F.L.A.:** 352 - **RPM:** 1755 - **Code:** L **Question:** Will it be possible to start this motor across the line, or will it be necessary to use a reduced-voltage starter to reduce starting current? ### Analysis To determine if you need a reduced-voltage starter, you need to compare the starting current of the motor with the maximum permitted starting current (3000 A). Typically, the starting current for a motor is 5-7 times the full-load current (F.L.A.). Given the motor's full-load current (F.L.A.) is 352 A: - **Estimated Starting Current Range:** - Lower Estimate: \( 352 \, \text{A} \times 5 = 1760 \, \text{A} \) - Higher Estimate: \( 352 \, \text{A} \times 7 = 2464 \, \text{A} \) Since both estimates (1760 A to 2464 A) are below the allowable maximum starting current of 3000 A, it is likely possible to start the motor across the line without needing a reduced-voltage starter. However, it is always recommended to further assess based on detailed motor specifications and practical testing to ensure compliance with all safety and operational standards.
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