There are a few possible reasons why an electric motor may not reach its nominal speed or has long acceleration times:

1. Incorrect power supply: The motor may not be receiving the correct voltage or frequency of power, which can cause it to run slower than its nominal speed or take longer to accelerate.

2. Mechanical issues: The motor may have mechanical issues such as misalignment, excessive load that can cause it to run slower than its nominal speed or have longer acceleration times.

3. Electrical issues: The motor may have electrical issues such as damaged windings or a faulty starter that can cause it to run slower than its nominal speed or have longer acceleration times.

4. Control system issues: The control system that is used to operate the motor may not be set up correctly or may be malfunctioning, causing the motor to run slower or have longer acceleration times.