SIEMENS Hygrostat 8MR2170-1AF EFR012 AC 230V

Controlling humidity inside electrical enclosures is a common challenge, as excessive moisture can lead to corrosion, short circuits, and premature failure of sensitive components. The SIEMENS Hygrostat 8MR2170-1AF EFR012 provides a reliable solution by automatically switching heaters or filter fans based on relative humidity levels, preventing condensation and maintaining a safe environment for your equipment.

Who is it for

This hygrostat is ideal for panel builders, maintenance technicians, and system integrators who need to protect electrical enclosures in industrial or commercial settings. It is particularly useful in environments where temperature fluctuations cause humidity buildup, such as outdoor installations, unheated rooms, or areas with high moisture.

Main features

• Adjustable humidity set point from 50% to 90% RH
• Switching difference approximately 4% RH to prevent rapid cycling
• Changeover contact (SPDT) for flexible control of heaters or fans
• Switching capacity up to 5 A at AC 250 V resistive load
• Mountable on 35 mm DIN rail or by screws for easy installation
• Compact plastic housing in light grey, protection class IP20

Specifications

• Operating voltage: AC 230 V
• Humidity setting range: 50–90% RH
• Switching difference: approx. 4% RH
• Contact type: changeover contact (SPDT)
• Switching capacity resistive: 5 A at AC 250 V
• Switching capacity inductive: 1 A at AC 250 V (cos φ = 0.6)
• Connection: screw terminals, max. wire cross-section 2.5 mm²
• Mounting: DIN rail 35 mm or screw mounting
• Protection class: IP20
• Operating temperature: -20 to +80 °C
• Storage temperature: -45 to +80 °C
• Sensor element: synthetic fabric band
• Housing material: plastic, colour light grey

Tips

Position the hygrostat in the upper part of the enclosure where warm, humid air tends to accumulate. Ensure the sensing element is not directly exposed to airflow from fans or heaters to avoid false readings. For best results, combine with a heater to raise the temperature above dew point and reduce relative humidity.