Okay, let's troubleshoot this problem with your SEW motor replacement. The key information is that the new motor is running at about half speed, and the nameplate specifies RPM values for both 50 Hz and 60 Hz. The fact that the RPM spec for 60Hz was stamped 1760/441 is also super important.Here's a breakdown of potential causes and how to investigate them

1. Frequency Mismatch (Most Likely Cause)
Explanation

Motors are designed to run at a specific frequency. In the US, the standard is 60 Hz. In Europe, it's 50 Hz. If you're in a 60 Hz environment and the motor is configured for 50 Hz, it will run at approximately 5/6th of its rated speed. 1760 5/6 = ~1467 so you are seeing the right speed for 50HZ if it is supposed to run 1760@60hz.

Action

This is almost certainly your problem. The nameplate shows the motor is capable of running at both frequencies, but it needs to be wired/configured correctly for the 60 Hz in your location.

Check the Motor Terminal Box

SEW motors (and most dual-frequency motors) have a connection diagram inside the terminal box. This diagram shows how to wire the motor for different voltages and frequencies.

Carefully compare the wiring configuration to the diagram. Make sure it's wired correctly for your voltage and 60 Hz operation. Voltage

Dual-frequency motors often have different voltage requirements depending on the frequency. The diagram will show this too. Double-check that your supply voltage matches the configured voltage for 60 Hz operation. A voltage mismatch could also cause speed problems, but it's less likely to be the sole cause.

2. Incorrect Gear Ratio (Less Likely, but Possible) Explanation

If the SEW motor has an integrated gearbox, there's a small chance the gear ratio of the new motor is different from the old one. This would affect the output speed.

Action



Compare Gearbox Information

Carefully compare the model number and any other markings on the gearbox of the old and new motors. If the model numbers are different, the gear ratios could be different. If the gear ratio is incorrect that would also affect the output speed and belt speed.

3. Motor Wiring Issues (Possible, but Less Likely if it's Running at All) Explanation

Incorrect wiring of the motor windings could cause speed problems, but it's more likely to prevent the motor from running at all.

Action



Verify Wiring Against Diagram

Double-check that each wire from the motor leads is connected to the correct terminal in the control panel or starter. Use the wiring diagram for the specific motor model.

Phase Rotation

While less likely in this scenario, incorrect phase rotation can cause issues. If you can easily reverse two of the incoming power leads, try that to see if it makes a difference.

Important: Only do this if you understand the potential consequences and can do it safely.4. Control System Problems (Unlikely, but Rule it Out) Explanation

If the motor is controlled by a Variable Frequency Drive (VFD) or other sophisticated control system, there could be a programming or configuration issue.

Action



Check VFD Settings (If Applicable)

If a VFD is used, verify that the motor parameters are correctly programmed into the VFD (voltage, frequency, current, RPM, number of poles). Also, confirm that the VFD is outputting the correct frequency and voltage.

5. Mechanical Binding (Unlikely if Speed is Consistent) Explanation

If there's excessive friction or binding in the driven equipment, it could slow the motor down. However, this usually manifests as inconsistent speed or the motor struggling to start.

Action



Inspect Driven Equipment

Disconnect the motor from the load (if possible and safe). Run the motor briefly unloaded to see if it reaches its rated speed. If it does, the problem is likely with the driven equipment.

Check Belt Tension

Make sure the belt tension is correct. Too much tension can create excessive load on the motor.

Regarding the Nameplate Information Frequency

As you've noticed, the nameplate clearly shows the motor is capable of running at both 50 Hz and 60 Hz.

RPM

The RPM values listed (1760/441) are the rated speeds at 60 Hz. The other RPM values are for 50Hz.

Frame Size

You're right. Often on nameplates (especially for IEC motors), the number after the slash in a frequency or voltage rating can sometimes relate to the frame size, but not always. Don't rely on that as a primary indicator. Frame size is usually specified separately on the nameplate, often with a letter code (e.g., 90L, 100L, etc.).

IEC vs. NEMA

SEW motors often use IEC (International Electrotechnical Commission) standards, especially in Europe and other regions. However, they can sometimes be built to NEMA (National Electrical Manufacturers Association) standards, particularly for the North American market.

Steps to Take Now


Safety First

Disconnect power to the motor before working on any electrical connections.2.

Locate the Terminal Box

Open the terminal box on the motor.3.

Find the Wiring Diagram

Look for the wiring diagram inside the terminal box. It's usually a sticker or a small metal plate.4.

Compare Wiring to Diagram

Carefully compare the actual wiring of the motor leads to the diagram. Pay close attention to the connections for your voltage and 60 Hz.5.

Take Pictures

Take clear pictures of the wiring before* you make any changes. This will help you if you need to revert back to the original configuration.6.

Make Adjustments (if necessary)

If the wiring is incorrect, carefully change the connections to match the diagram for your voltage and 60 Hz.7.

Double-Check Everything

Before applying power, double-check all connections to make sure they are secure and correct.8.

Apply Power and Test

Turn on the power and observe the motor speed. It should now be running at close to its rated speed.9.

If Still Problem

If the problem persists after checking the wiring, proceed to the other potential causes listed above.

Important Warning: If you're not comfortable working with electrical equipment, it's best to call a qualified electrician or motor technician. Incorrect wiring can damage the motor or create a safety hazard. Flag for review