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Glossary

Scroll compressor

A compressor that squeezes vapour between a fixed and an orbiting spiral.

A scroll compressor traps vapour between two interleaved spirals and compresses it toward the centre as one spiral orbits. They are common in residential and light commercial equipment. A three-phase scroll wired with the wrong phase sequence runs backwards: it is noisy, draws low current and builds no pressure difference. Stop it quickly and swap two supply legs with the power locked out.

Exam work areas

E · Commissioning and start-up F · Maintenance, service and troubleshooting