Reciprocating refrigeration compressor motor starter, contactor inspection and overload protection setting principle

Reciprocating refrigeration compressor motor starter, contactor inspection and overload protection setting principle

Motor starter controls power supply to compressor motor; contactor contact ablation, coil aging and incorrect overload setting are common causes of unexpected shutdown. Motor overload protection shall be set at 1.05 times of rated motor current; protection shall trip within 10 minutes under 120% rated current continuous load. Xiteliduo reciprocating compressor adopts AC contactor with silver alloy contacts; contact surface ablation depth over 0.5 mm requires contactor replacement. Small 4-cyl reciprocating refrigeration compressor direct-on-line starter is widely used; large starting current creates contact arc erosion during every startup. Medium 4-cyl reciprocating refrigeration compressor contactor coil failure often happens under high ambient temperature; high temperature accelerates coil insulation aging. Large 4-cyl reciprocating refrigeration compressor adopts star-delta starter to reduce inrush current; wrong wiring will cause phase current imbalance and motor overheating. Large 6-cyl reciprocating refrigeration compressor high rated current requires periodic contact resistance test; contact resistance rise indicates hidden contact degradation. Many maintenance teams never check contactor contact condition, only reset overload protection after trip. This practice increases sudden motor trip risk by 47%. Single-unit two-stage refrigeration compressor low-stage and high-stage have independent motor starters; interlock logic prevents high-stage startup before low-stage is ready. Cascade unit high-stage reciprocating refrigeration compressor starter interlocks with low-stage pressure signal; high-stage motor cannot start if low-stage pressure is abnormal.

FAQ

Q1: What is the overload protection setting standard for reciprocating compressor motor? A1: Set to 1.05 × rated motor current; trip within 10 min under 120% rated current. Q2: What contact defect requires replacement of Xiteliduo AC contactor? A2: Contact ablation depth deeper than 0.5 mm. Q3: What wears contacts of small 4-cyl compressor direct-on-line starter? A3: Large starting current generates electric arc erosion on contact surface. Q4: What factor accelerates medium 4-cyl compressor contactor coil aging? A4: High ambient temperature around electrical cabinet. Q5: What fault will be induced by wrong star-delta starter wiring on large 4-cyl compressor? A5: Three-phase current imbalance and motor overheating. Q6: What risk increases if contactor inspection is skipped and only overload reset is done after trip? A6: Unexpected motor shutdown risk rises by 47%. Q7: What interlock rule applies to single-unit two-stage compressor starters? A7: High-stage cannot start until low-stage unit is ready.