DANFOSS 060B017266 MP 54 Differential Pressure Switch

Product Overview

The 060B017266 (060B017266) is a high-precision differential pressure switch from the Danfoss MP 54 series, specifically engineered to act as an oil pressure safety control for refrigeration compressors. This specialized switch monitors the pressure difference between the oil lubrication system and the suction pressure within the crankcase. The 060B017266 features a built-in thermal time relay that provides a critical safety delay, preventing the compressor from tripping during short-term pressure fluctuations during startup. If the differential oil pressure fails to reach the required level within the set time, the switch de-energizes the compressor to prevent mechanical failure. This model has been officially succeeded by the 060B017291, which maintains the same core functionality and reliability for industrial cooling and HVAC systems.

Technical Configuration

The MP 54 series utilizes a dual-bellows mechanical system combined with an electrical delay circuit for fail-safe monitoring:

• Dual Bellows System: Incorporates two separate pressure bellows—one for oil pressure and one for suction pressure. The switch activates based on the physical difference between these two inputs.

• Thermal Time Relay: Integrated with a factory-set thermal relay that allows the compressor to run for a specific duration (typically 45, 60, or 90 seconds) without sufficient oil pressure before initiating a safety shutdown.

• Factory Calibration: Pre-set at a differential of 0.65 bar (9 psig), providing a reliable baseline for most industrial semi-hermetic and open compressors.

• High Test Pressure: Capable of withstanding a maximum test pressure of 22 bar (319 psig), ensuring the bellows remain intact during system pressure testing or abnormal high-pressure conditions.

• Bellows Durability: Designed to handle high temperatures, with the bellows rated for short-term exposure up to 100 deg C.

Technical Specifications

Technical FAQs

Why has the 060B017266 been replaced by the 060B017291?

Product replacements in the Danfoss MP series are typically driven by manufacturing process optimizations or material updates. The 060B017291 serves as a direct functional replacement, offering the same 0.65 bar factory setting and terminal layout to ensure a drop-in transition for existing maintenance requirements.

How does the thermal time relay function in this switch?

When the compressor starts, the thermal relay is energized. If the differential oil pressure does not rise above the setpoint (0.65 bar) within the specified time, the heater in the relay trips the mechanical contact, cutting power to the compressor contactor. This ensures the compressor is never operated without lubrication for a dangerous length of time.

Is the 060B017266 compatible with all refrigerants?

The MP 54 series is compatible with all common fluorinated refrigerants (HFC, HCFC, CFC). However, for applications involving ammonia (R717), specialized versions with stainless steel bellows must be used to prevent chemical corrosion.

Engineering & Installation Guide

• Wiring for Safety: The thermal time relay must be wired in series with the compressor's control circuit. Ensure that the voltage supplied to the thermal relay (terminals L and M) matches the system's control voltage to avoid burning out the internal heating element.

• Pressure Connection: Connect the "OIL" bellows to the discharge side of the oil pump and the "LP" bellows to the compressor crankcase (suction side). Use capillary tubes with vibration-damped loops to prevent mechanical stress on the bellows connections.

• Manual Reset: The 060B017266 is a manual reset device. After a trip occurs, the technician must investigate the cause of the oil pressure loss before pressing the reset button. Frequent tripping indicates a serious lubrication issue or a failing oil pump.