Nema Mg1-32 Amp- 33 | ((install))
The most famous line from this section states: "For motors rated 600V or less, the peak voltage at the motor terminals shall not exceed 1,000V for rise times of 0.1 microseconds or greater."
The "AMP" may be a typographical or shorthand addition, possibly stemming from "MG1 Part 33" or "MG1-33." Others interpret "AMP" as referring to mperes or A pplication M anual P art 33. However, the industry consensus is that when you search for NEMA MG1-32 AMP-33 , you want MG1-32 (insulation) and MG1-33 (bearing protection) . What is MG1-33? MG1-33 addresses a phenomenon that became widespread with the adoption of VFDs: electrical bearing damage. nema mg1-32 amp- 33
If you have ever dealt with premature motor failure, mysterious bearing pitting, or insulation breakdown in variable frequency drive (VFD) applications, you have likely encountered the need to comply with these sections. This article provides a deep dive into NEMA MG1-32 and AMP-33, explaining what they mean, why they matter, and how to apply them to protect your motor investment. Before dissecting Sections 32 and 33, it is essential to understand the parent document. NEMA MG1 (National Electrical Manufacturers Association Standards Publication No. MG1) is the North American gold standard for Motors and Generators . The most famous line from this section states:
| Threat | NEMA Section | Failure Point | Solution | | :--- | :--- | :--- | :--- | | Voltage spikes & corona | | Stator windings | Phase paper, VPI, inverter-duty wire | | Shaft voltage discharge | MG1-33 (AMP-33) | Bearings | Insulated bearings, grounding rings | MG1-33 addresses a phenomenon that became widespread with
Specifically, when a motor is operated by a , the drive does not output a pure sine wave. Instead, it uses Pulse Width Modulation (PWM), which creates voltage spikes and rapid switching transients. The Key Specification: MG1-32 (Part 31.4.4.2) While not always numbered identically across MG1 revisions, the critical requirement for VFD-duty motors is found in MG1-32’s sections on Voltage Stress . It mandates that inverters used with motors must comply with certain peak voltage limits.