Danfoss 060-110166 KP 1 Low Pressure Switch -0.2 to 7.5 bar

A KP 1 low-pressure switch with automatic reset for compressor protection

The 060-110166 is the Danfoss KP 1, the standard low-pressure member of the KP range. A single bellows element senses the suction pressure at its 1/4 in male flare connection and flips an SPDT snap-action contact when the pressure falls to the cut-out value, then flips it back when the pressure has recovered by the set differential. Regulation covers -0.2 to 7.5 bar, so it handles everything from deep vacuum-side protection up to typical R404A or R134a suction levels, and the automatic reset means the compressor restarts on its own once suction pressure returns.

Danfoss describes the KP series as protection against excessively low suction pressure or excessively high discharge pressure, and as a way to start and stop compressors and condenser fans. The contact can drive a single-phase AC motor of about 2 kW directly; larger motors and DC loads are switched through a contactor in the control circuit. This particular code carries the IP44 enclosure option rather than the open IP30 version, which makes it a better fit for plant rooms where condensation or splashing is possible.

Technical specifications

Setting the cut-in, cut-out and differential

Two spindles under the cover set the switch. The range spindle fixes the cut-in pressure on the scale, and the differential spindle moves the cut-out below it. With a 0.7 to 4.0 bar differential window, a cut-in of 2.0 bar and a differential of 1.0 bar gives a cut-out at 1.0 bar. Keep the differential wide enough to prevent short-cycling of the compressor, and choose the cut-out from the lowest suction pressure your refrigerant and evaporator allow.

A manual trip lever lets you test the contact function without any tools and without changing pressure, which is useful during commissioning. The data sheet also lists a fail-safe double-bellows construction for the KP 6, KP 7, KP 17 and KP 47 types; the KP 1 uses the single welded bellows, so where a failure of the element itself must lead to a safe state, discuss the alternative types before ordering. The store entry for this code notes that it is not applicable for a liquid line.

Installation notes and what to confirm before ordering

Mount the switch on a flat, vibration-free surface and keep the pressure line short and clean so that dirt and oil do not collect at the bellows. Run the cable through the supplied rubber gland for 6 to 14 mm cables and terminate it according to the diagram inside the cover. Check that the cabinet or plant room fits the ambient window of -25 to 65 C.

Confirm the refrigerant against the approved list printed for this code on the Danfoss product page, the supply voltage and load of the contact, and whether you need auto or manual reset, because the KP 1 is built in several reset and connection versions that carry different code numbers. Seven Star LLC is an independent supplier in Muscat; send us this code number together with the refrigerant and the required setting and we will check availability.

Commissioning the KP 1 on a refrigeration system

Connect the switch to a point on the suction line where it sees true suction pressure, and avoid positions directly after valves or restrictions where pressure can fluctuate. Run the connecting line so that it cannot vibrate against the pipework or frame, and secure it with suitable clips. Tighten the 1/4 in flare connection carefully and leak-test it with the method used for the rest of the system.

Before starting the compressor, set the cut-in and differential from the system design values and confirm them with a calibrated gauge rather than relying only on the scale. During the first run, slowly reduce suction pressure, for example by closing the liquid line valve under supervision, and note the pressure at which the contact opens and the pressure at which it closes again. Adjust the spindles if the measured values differ from the target, and use the manual trip lever to confirm that the control circuit reacts as intended.

Wiring checks

Wire the SPDT contact according to the control circuit diagram, using the rubber cable gland with a cable inside its stated diameter range so that the IP44 enclosure is maintained. Check that the switched load stays within the contact ratings on this page and route larger motors through a contactor.

Plant room conditions in Oman and the GCC

Condensing units and cold rooms in Oman and the GCC often run in very hot plant rooms or on exposed rooftops. Keep the switch out of direct sun and away from hot discharge lines, and check that the ambient at the mounting point stays within the temperature range listed in the specification table. Dust and sand can enter through a poorly sealed cable entry or a cover left loose after adjustment, so refit the cover correctly after every setting change. In humid coastal sites, mount the switch so that condensate from cold pipework cannot drip onto it.

Periodic maintenance

During scheduled service visits, compare the actual cut-out and cut-in pressures with the commissioning record, inspect the flare joint for oil traces that indicate a leak, and check that the cable gland and cover are still sealed. If the compressor starts cycling frequently on low pressure, look first at the refrigerant charge, evaporator airflow and filter drier before changing the switch setting.

Documents and quotation

The attached file is the Danfoss KP pressure switch data sheet (AI552626450143), which covers the full KP 1 to KP 47 range, wiring, dimensions and ordering tables. For other pressure switches and thermostats see our pressure instrumentation category. Request a quotation with the code 060-110166 and quantity.