Final answer:
An oil pressure safety control with a 90 second time delay is designed to protect a compressor from damage by preventing premature shutdowns during transient conditions where oil pressure may not have stabilized.
Step-by-step explanation:
An oil pressure safety control is a critical component in refrigeration and HVAC systems to protect the compressor from damage due to low oil pressure. The reason for the built-in 90 second time delay is to prevent the system from shutting down prematurely during transient conditions such as start-up, where it is normal for oil pressure to take a moment to build up to the required level. If the compressor were to shut down without this delay, it could lead to unnecessary wear and could also cause safety issues. The time delay allows the system to stabilize, ensuring that any shutdown is truly due to a persisting issue with the oil pressure rather than a temporary fluctuation.