Pressure relay KP35 1/4" (Danfoss)

Danfoss KP 35 is a professional and compact solution for the automation of water supply systems. This device is designed to control the starting and stopping of pumps based on system pressure, ensuring stable water delivery and protecting equipment from unnecessary strain.

Application

This switch is used for the direct control of pumps in water supply lines. It monitors the pressure in the piping, automatically starting the pump when pressure drops below the set level and stopping it when the required upper threshold is reached.

Key Advantages

• High Response Speed: An ultra-short reaction time and "click-action" function ensure immediate and precise contact switching.

• Vibration Resistance: The design withstands vibrations in the range of 0–1000 Hz at 4 g acceleration, allowing for installation directly near operating machinery.

• Reliable Contacts: Made of gold-plated silver (Ag), preventing burning or sticking and guaranteeing a long service life.

• Versatility: Suitable for use in both alternating current (AC) and direct current (DC) networks.

• Compact Size: Small housing dimensions (84x61x44 mm) significantly simplify installation in confined spaces.

Technical Specifications

• Regulation Range: from -0.2 to 7.5 bar.

• Adjustable Differential: from 0.7 to 4 bar.

• Ambient Temperature: from -40^{\circ}C to +65^{\circ}C (up to +80^{\circ}C for short periods).

• Medium Temperature: from -40^{\circ}C to +100^{\circ}C.

• Contact Type: Single Pole Double Throw (SPDT).

• Contact Material: Gold-plated silver (Ag).

• Enclosure Class: IP 33.

• Connection: External thread G 1/4 A.

Wiring and Principles

The device utilizes a 1-2-4 contact system. For standard pump control in a water supply system, terminals 1 and 4 are used:

• Terminal 1 (Common): The power phase is connected here.

• Terminal 4: Closes as pressure drops. This is used to start the pump.

• Terminal 2: Opens as pressure drops. This can be used to connect a signal lamp or alarm.

Setting the Switch

The switch is easily adjusted to your system's needs using the two regulation shafts on top of the housing:

1. Main Scale: Sets the pump cut-out pressure (the upper limit).

1. DIFF Scale: Sets the difference between the cut-out and cut-in pressure (e.g., if cut-out is 4 bar and DIFF is 1.5 bar, the pump will start at 2.5 bar).