Pfannenberg FLZ 600 Hygrostat for Control Cabinets, 40-90 % RH

Humidity control that keeps condensation out of the enclosure

The Pfannenberg FLZ 600 is a mechanical hygrostat that switches an enclosure heater or filterfan when the relative humidity passes a preset value. Its sibling, the FLZ 610, is an electronic combination device that monitors temperature and humidity independently in one housing. Both clip onto a 35 mm DIN rail.

Keeping relative humidity below the dew-point condition prevents water condensing on electrical components and stops corrosion of unprotected sheet metal. This matters in coastal locations and in enclosures that cool down quickly after a hot day, where humid air inside the cabinet condenses on the first cold surface.

Technical specifications

Choosing between the mechanical and the electronic version

The FLZ 600 is the economical choice where one humidity set point switches one heater or fan. Its polyamide belt probe changes length with humidity and operates the changeover contact, so it needs no supply voltage. The FLZ 610 is the better choice where temperature and humidity both matter: it monitors the two quantities independently, shows operation with an LED and uses a relay output with a contact resistance below 10 milliohm, which suits the small signal currents of control systems as well as heater loads.

In practice the hygrostat is wired in parallel with a thermostat. The thermostat holds a minimum enclosure temperature, and the hygrostat adds heater or fan operation when humidity rises above the set value, even though the temperature is within range. Both devices are listed on the product sheet as accessories for the thermostat and heater range, with a matching internal enclosure fan, article number 18110000000, to circulate air so that the probe sees typical conditions.

What to confirm before ordering

Confirm the supply (the FLZ 610 needs 230 V AC), the load and its rating, and whether the application needs a humidity control only or a combined humidity and temperature control. Fit the device away from heater outlets and fan streams so that it measures cabinet air and not a local hot or dry spot, and allow for the 5 % switching difference of the mechanical version when choosing the set point. The sheet states the operating range 0 to +60 °C for the FLZ 600 and -20 to +60 °C for the FLZ 610.

How the Pfannenberg FLZ 600 works

A belt of polyamide in the device grows longer as the air gets more humid and shorter as it dries. The belt moves a spring contact. When the humidity passes the set value, the contact changes over and switches the heater or the filter fan. The device needs no supply voltage to do this.

Where the FLZ 600 is used

• Control cabinets in coastal locations
• Outdoor enclosures
• Switchgear panels
• Enclosures that cool fast after a hot day
• Cabinets with unprotected sheet metal

Selection checklist for the FLZ 600

• Humidity set point
• Heater or fan to switch
• Contact rating
• Mechanical or electronic type
• Need for a thermostat
• Mounting on a DIN rail
• Cabinet temperature range
• Space inside the cabinet

Installation, commissioning and maintenance notes for the FLZ 600

Clip the hygrostat onto the 35 mm DIN rail in the air flow of the cabinet. Keep it away from the heater outlet. Wire the contact to the heater or fan circuit. Set the humidity value on the scale. Check the switching after a long idle period.

Requesting a quotation for the Pfannenberg FLZ 600

Please send the humidity set point and the load to be switched. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

FLZ 600 setting range

The setting range is 40 to 90 percent relative humidity.

FLZ 600 type

The FLZ 600 is a mechanical hygrostat.

FLZ 600 contact

It has a changeover contact with a spring contact.

FLZ 600 switching difference

The switching difference is about 5 percent.

FLZ 600 normally closed rating

The normally closed contact switches 24 to 250 V AC at 2 A.

FLZ 600 normally open rating

The normally open contact switches 24 to 250 V AC at 5 A.

FLZ 600 temperature range

It works from 0 to 60 degrees C.

FLZ 600 protection

The protection class is IP30.

FLZ 600 probe

The probe is a polyamide belt.

FLZ 600 mounting

It clips onto a 35 mm DIN rail.

FLZ 600 size and weight

It measures 37 x 60 x 47 mm and weighs 55 g.

Hygrostat records for the FLZ 600

Record the set value, the cabinet location and the date of each switching test.

Choosing the right FLZ 600 setting

Set the value so the heater starts before the air in the cabinet reaches dew point.

Documents and quotation

The Pfannenberg FLZ 600/610 product sheet is attached to this page and is the manufacturer’s own document, not a Seven Star summary. It includes dimensions and the accessory table. Heaters and filterfans that these devices control are listed in HVAC & Combustion and Cooling.

State which of the two devices, or both, is required. Seven Star LLC, an independent supplier in Muscat, quotes the FLZ 600 and FLZ 610 against your application data; send the enclosure size, ambient temperature, supply voltage and quantity so the correct variant and article number can be confirmed before an offer is issued.