Why does a timer fail to stop at the set time?

Possible causes include motor or board failure, welded contacts, mechanical sticking or wrong wiring. Stop and repair if it fails to switch off on time. Checklist: Define capacity, accuracy, materials and operating environment before requesting quotes on a uniform basis. Request specification sheets, test reports, certificates, maintenance manuals and spare-part lists. During acceptance, verify appearance, dimensions, functions, safety protection and packaging, and keep test records. Do not compare unit price alone; include customization, freight, spare parts, after-sales support and downtime risk. Keep written records of inquiries, confirmations, FAT, acceptance and warranty commitments.