Routine Tests on Motor
The rated speed is not 1500 RPM, that is the synchronous speed. The no-load speed should be quite close to the synchronous speed even at reduced voltage. If the rated speed is 1460 RPM, that is the speed for full-voltage, full-load operation. That requires a dynamometer to check. The reduced voltage test is probably the only no-load test that is part of routine testing. The locked-rotor test is probably not part of routine testing. The manufacturer may have an acceptable range of current that can be checked as part of the reduced voltage test. However if the standard doesn't specify that that should be checked, it is not a requirement to check it.