LG MBT021WMA Scroll Compressor – 3 HP, R404A, 5,919 W / 20,196 BTU/h, 380-420 V 3-Phase

LG MBT021WMA is a 3 HP scroll hermetic compressor manufactured for commercial refrigeration. It operates with R404A and has a 380-420 V three-phase supply. At condensing 40 °C / evaporating −10 °C it delivers a cooling capacity of 5,919 W (20,196 BTU/h).

Scroll Technology: Fewer Parts, Quieter Operation, High Efficiency

A scroll compressor has no valves, piston rings or crank-connecting rod assembly as in the reciprocating type; compression takes place continuously and in one direction between two scrolls. In the field this means three things: fewer moving parts (smaller failure surface), lower vibration and noise, and a design that is more tolerant of liquid slugging.

In addition, the compression chamber of a scroll compressor empties completely on each revolution — there is no clearance volume. This means higher volumetric efficiency than an equivalent reciprocating compressor, especially at low evaporating temperatures.

Nominal Cooling Capacity (W)

Return gas temperature 18.3 °C · subcooling 0 °C · ambient 35 °C · 50 Hz · values have a ±5% tolerance.

How to read the table? The row on the left is the condensing temperature at which your condenser operates, and the column at the top is the evaporating temperature of your evaporator. In hot climates or with a dirty condenser, the condensing temperature rises: the same compressor operating at 55 °C instead of 40 °C delivers 4,425 W instead of 5,919 W at −10 °C. Make your selection based on your actual operating conditions.

Technical Specifications (Official LG Performance Document)

• Model: LG MBT021WMA · scroll hermetic compressor
• Power: 3 HP · refrigerant: R404A
• Power supply: 380-420 V / 50 Hz · 460 V / 60 Hz · three-phase
• Running current: 6 A
• Starting current (LRA): 58 A — use this value as the basis for fuse and contactor selection
• Max. operating current: 8 A — the overload relay is set according to this value
• Suction tube: 7/8" · discharge tube: 1/2"
• Capacity (ASHRAE 7.2 °C / 54.4 °C): 8,441 W
• Application: commercial refrigeration · cold rooms · blast freezer rooms · supermarket display case racks

• 🔧 Phase sequence is critical. A scroll compressor rotates in one direction only. If the phase sequence is reversed in a three-phase connection, the compressor runs backwards: pressure does not build up, noise rises abnormally and it is damaged in a short time. At first start-up, verify that the discharge pressure rises; if it does not, swap two phases.
• 🔧 Electrical installation: the starting current rises to 58 A. Select the contactor, fuse and cable cross-section according to this value; set the overload relay to the 8 A maximum operating current. Use a phase protection relay — phase loss, phase sequence error and undervoltage are the three most common causes of scroll compressor failure.
• 🔧 Crankcase heater: Prevents refrigerant migration into the oil during standstill. After long standstills, it is recommended that the heater be energized for at least 8-12 hours before starting the compressor.
• 🔧 Use a suction line filter and a filter drier in the liquid line. Scroll wraps have tight tolerances; solid particles entering the system cause direct wear.
• ⚠️ Oil and moisture: POE oil is used with R404A, and POE is hygroscopic; do not leave the lines open and pull a full vacuum.
• Application limit: This model is for R404A. Use with other refrigerants requires manufacturer approval.