What instrument should an engineer use to check for shorts in the motor windings?

The correct choice for checking for shorts in motor windings is the ohmmeter. An ohmmeter measures electrical resistance and is particularly useful for identifying shorts because it can reveal low resistance pathways that shouldn't be present in a functioning motor. When testing motor windings, one typically looks for continuity and the amount of resistance in the coil windings. A short circuit will show a very low resistance reading, indicating that there is a direct connection where none should exist.

In the context of motor testing, using an ammeter would measure current flow rather than resistance, which is not suitable for diagnosing shorts. A voltmeter measures voltage, which is useful for other aspects of electrical diagnostics but does not provide the resistance information needed to identify shorts. A multimeter, while capable of measuring resistance, voltage, and current, would require setting it specifically to the resistance function to be effective in checking for shorts. However, the most focused tool for this specific task of checking for shorts is the ohmmeter, making it the best choice in this situation.