Protector mismatch means a wasted 15-day locked-rotor run - a two-station bench with automatic four-check safety judgement

Model: NL-YSDZ-2

The problem

Protector selection by guesswork buries a locked-rotor hazard in a whole batch of orders: how hot the windings get with the rotor jammed and whether the protector trips is only discovered in a user kitchen, which means fire risk and recalls. GB 4706.17 requires the compressor to stay safe under locked-rotor conditions, and a proper verification runs 15 days continuously with 6000-9000 protector actions - impossible to supervise by hand while keeping grounded/hipot/insulation/flow records in sync.

Capability

Two stations alternate between two compressors; supply switches between single and three phase with up to 100A per station. Suitable for single/three-phase refrigeration compressors up to 1P (pre-charged with oil): lock the rotor, charge refrigerant and oil, connect the test loop, apply rated voltage and the bench records the cold locked-rotor current after 4 seconds - the point marked on the protector initial-trip curve that starts protector matching. Life tests run in two modes: continuously for 1-9999 hours, or intermittently for 1-99999 on/off cycles with 1 second to 300 hours per interval, driven by a 15kW inverter through terminal control. Four safety checks run on line: earth resistance 600 milliohm at 3-30A, hipot 0-5000V AC at 30mA, insulation DC 500-1000V to 9999 megohm, and no-load flow 0-20L/min, any NG stopping the test with an alarm; judgement requires winding temperature below 130C and shell below 150C. Voltage 50-250V at 0.5 percent, 50/60Hz. Automatic mode is set from the industrial PC software which stores all results; manual mode is set from the touch screen. The test loop carries ball valve, air-conditioning group, solenoid valves, filter, charge vessel, back-pressure valve, silencers, pressure transmitters and switches, gauges, flow meter and safety valve; compressors load into the lower bay behind a safety door.

Key specifications

• Application: locked-rotor endurance of motor-compressors per GB 4706.17
• Stations: 2, alternating
• Supply: single/three phase switching, 100A max per station
• Samples: single/three-phase refrigeration compressors up to 1P, pre-charged with oil
• Recording: cold locked-rotor current at 4 s automatically logged
• Voltage: 50-250V at 0.5 percent; frequency 50/60Hz
• Inverter supply: 15kW, terminal-controlled on/off cycling
• Earth resistance: 0.5-9.9s, 3-30A, 600 milliohm, 2 percent
• Hipot: 0.3-9.9s, AC 0-5000V, 30mA, 2 percent
• Insulation: 0.5-9.9s, DC 500-1000V, to 9999 megohm, 2 percent
• No-load flow: 4.0-9.9s, 0-20L/min, 1 percent
• Continuous life: 1-9999 hours

Applications

Protector matching and outgoing locked-rotor verification at compressor plants; incoming locked-rotor and safety sampling by appliance makers; motor-compressor safety and endurance testing at third-party laboratories; coil and protector development screening

About the manufacturer

Guangdong Endurance Electronic Equipment Co., Ltd provides non-standard customization, drawing confirmation, factory acceptance, on-site installation and commissioning, operation training and long-term technical service; 12-month warranty and long-term spare parts supply. Tel: 0760-88500902 / 13416787649. Web: en.zsnaili.com.