(formerly known as ECO 842T-Series)

Low thermal Reed Relays

The Reed Relays of the BT-series are low thermal relays with 2 form A switches (form B switches are also available) working with a thermal voltage of only 1 µ at 100% duty cycle. This extremely low thermal voltage is achieved through an optimized temperature balance between the Reed Switches and the minimum energization power of the coil enabling the relays of the BT-Series to switch lowest signals down to the microvolt range.

Typical applications:

  • Test, measurement and control technology
  • High precision measuring devices
  • Change-over switch for measuring points of thermoelectric elements and resistance thermometers
  • Recorder input


Tolerance +/- 0.10mm (0.004 inch)

Relay Data

Operating temperature (°C) -20/+70
Storage temperature (°C) -40/+105
Isolation coil/contact min. (kVAC) 2.0
Isolation coil/contact/casing min. (kVAC) 1.0
Insulation coil/contact min. (Ohm) 1012
Thermal voltage at 100% duty cycle (µV) <1
Life expectancy Dependent upon load, consult factory
Soldering time/temperature max. 5 sec./260 °C
Cleaning Fully sealed

Contact Data

Contact type 71
Contact form A/dry
Rated power max. (W) 10
Switching voltage max. (VDC) 200
Switching current max. (A) 0.5
Carry current max. (A) 1.0
Contact resistance max. mOhm 150
Insulation resistance min. Ohm 1010
Breakdown voltage min. (VDC) 250
Operating time incl. bounce typ. (ms) 0.8
Releasing time typ. (ms) 0.1
Shock at 11 ms max. (g) 150
Vibration at 10 – 2000 Hz. max. (g) 10

Coil Data with contact form 2A (Data at 20°C)

Contact form Contact type Nominal voltage
Coil resistance
+/- 10%
Pull-in voltage
Drop-out voltage
Nominal power
2A 71 5 900 56 3.8 1.0 27
12 5100 9.0 2.0 28
24 20500 18.0 3.5 28

Other coil resistance values on request

Diagram view from component side (pitch 2.54 mm / 0.1 inch)

Order information

Example for ordering

BT 05 – 2A71

BT relay, 5V coil voltage, 2 form A switches 71

Part Inquiry

Your Name (required)

Your Email (required)

Your Address (required)

City (required)

State (required)

Zip (required)

I am interested in

Additional Commments