Which factor helps ensure the drive is sized for peak conditions by accounting for variability and surges?

• A. Efficiency factor
• B. Duty factor
• C. Temperature factor
• D. Service factor

Answer: (D)

When sizing a drive for peak conditions, you want a cushion for variability and surges in load. That cushion is provided by the service factor, which is a multiplier on the rated capacity to cover those unpredictable demands. It recognizes that real-world operation isn't perfectly steady—startups, accelerations, shocks, and slight condition changes can push the load above the nominal rating. So, with a service factor, you size the drive to handle higher-than-nominal loads; for example, a 10 HP drive with a service factor of 1.25 is treated as capable of about 12.5 HP during peak conditions. The other factors don’t serve this purpose: efficiency relates to energy loss, duty factor concerns how often and how long you run at rated load, and temperature factor adjusts for temperature effects rather than surge capacity.