Why Do DC Motors Show Voltage Rise While AC Loads Collapse in Inductive Tests?

Thread Starter

Lanikai

Joined Jul 3, 2026
1
Hello everyone,

I recently performed a set of inductive load tests using five devices:
• Two DC motors
• One AC motor
• One transformer
• One LED bulb

The results were interesting:

• Both DC motors showed a noticeable voltage rise when the inductive load was applied.
• All AC devices collapsed instantly (voltage dropped to near zero).
• The transformer and LED also showed immediate voltage drop with no rise effect.

I’m trying to understand why DC motors respond with a voltage increase, while AC loads collapse immediately.

Is this related to back EMF behavior, inductive kick characteristics, or something specific to DC motor winding topology?

Here is the full experiment video with data and graphs:

I’d appreciate any explanations or theories.
 

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