NT 78-M Thermo Hygrostat

The electronic Thermo Hygrostat senses the ambient temperature and relative humidity in an enclosure with electric/electronic components and turns on a heater (or alternatively a fan) at either set point, helping prevent the formation of condensation in the enclosure. Due to its wide voltage range the hygrotherm can be utilised anywhere in the world.  The LED integrated in the adjustment knob on the active controller is lit when the connected device is in operation.

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  • Temperature and humidity adjustable
  • Wide voltage range
  • Operating temperature down to -40°C
  • High switching capacity
  • Status indicator (LED)


NT 78-M
Switch difference temperature: 2K (±1K tolerance) at +25℃ (+77℉), 50% RH

humidity: 4% RH (±1% tolerance) at +25℃ (+77℉), 50% RH

Reaction time (humidity) approx. 5 sec.
Contact type change-over contact (relay)
Service life VDE NO/NC > 15,000 cycles; UL: NO/NC > 30,000 cycles
Max. switching capacity (relay output) 240VAC, 10(1.6) A / 120VAC, 15(1.6) A
Max. inrush current AC 30A for 10 sec.
Optical indicator LED
Connection 5-pole terminal, clamping torque 0.5Nm max.: rigid/stranded¹ wire 2.5mm² (AWG 14)
Mounting clip for 35mm DIN rail, EN 60715
Casing plastic according to UL94 V-0, light grey
Dimensions 77.5 x 60 x 37.5mm
Weight approx. 0.2kg
Fitting position vertical
Operating/Storage temperature -40 to +60℃ (-40 to +140℉)
Operating/Storage humidity max. 90% RH (non-condensing)
Protection type IP20

¹ When connecting with stranded wires, wire end ferrules must be used.

Art. No. Setting Range Temperature Setting Range Humidity Operating Voltage
860666 0 to +60℃ 50 to 90% RH 230VAC, 50/60Hz
860667 +32 to 140℉ 50 to 90% RH 120VAC, 50/60Hz
860668 0 to +60℃ 50 to 90% RH 120VAC, 50/60Hz