DT920 Intrinsically Safe Tachometer

Product features

  • NAMUR, switching transistor, contact inputs
  • 4 limit outputs
  • 4-20 mA scalable analog output
  • The following parameters can be set: teeth number, transmission ratio, limit values, 4-20 mA scale
  • Large (25 mm) LCD
  • Intrinsically safe, usable in potentially explosive environment
  • IP 65 protection

Product description

The DT920 Intrinsically Safe Tachometer enable the revolutions per minute (RPM) of a shaft of a spin-dryer, of a stirrer etc. to be displayed in even the most hazardous plant areas (zone 1, 2). Various kinds of two wire sensors (magnetic, optical, with NAMUR, transistor, contact output) are possible to connect to the input of the instrument.
The DT920 receive the impulses generated by the sensor, the parameters, that is: the number of teeth of the dial, the transmission ratio can be set by using the front panel membrane keypad.
The instrument have four optically isolated transistor outputs for limit signalling or for simple control purposes.
The DT920 optionally may be equipped with a 4-20 mA transmitter output. The output is scalable: the 20 mA value can be assigned to any RPM values. The output can be used either for signal processing, or for the operation a secondary display.
The DT920 is housed in a moulded polycarbonate case which is dust-tight and houseproof to IP 65 to, allow for installation in the field or on the control panel.
Large 4 digit, 25 mm height liquid crystal display make RPM value easily visible at a distance.

Technical specifications

Safety data:
The connection terminals of the supply voltages are isolated from each other, the isolation is in compliance with the standard EN 61010-1, taking into consideration the following:
Pollution level:2
Measurement category:II
Intrinsical safety data:
Certification:BKI 15 ATEX 0036 X
Protection marking: II 2G Ex ia IIC T4 Gb (-20 °C < Ta < +60 °C)
Safety data pertaining to intrinsical safety:
Uo [V]Io [mA]Po [mW]Co [uF]Lo [mH]Ui [V]Ii [mA]Pi [W]Ci [uF]Li [mH]
Power supply:----------22.4912.100.73
NAMUR input:8.618.7237.55100----------
Digital outputs:51.351.60030350.200
Analogue outputs:8.6149.7107510----------
Input parameters:
Digital inputs:
Input:for the connection of NAMUR (DIN 19234) / contact / switching
No-load voltage / inner resistance:8.2 V / 1 kohm
Frequency range:0.3-5000 Hz
Output parameters:
Analogue output:
Output signal:DC current
Range:4-20 mA
Overvoltage protection:8.6 V (limiter)
Overcurrent protection:50 mA (limiter)
Error of the output signal:0.5% (max.)
Temperature-coefficient:50 ppm / OC (typically)
Supply-voltage effect:practically zero
Loading-effect:practically zero
Digital outputs:
Output:4 passive switching transistor
Load rating:30 V, 35 mA, 200 mW
Display / manual controls:
Display:4 digit LCD, 7 segments, decimal point
Display unit:25 mm character height
Display range:0.000-9999
Accuracy:±1 digit
Indicators:4 LED for limit values
Manual controls:4 push-buttons on the front cover
Power supply:
Supply voltage:18 VDC (intrinsically safe)
Supply current:70 mA
Consumption:1.4 W (max.)
Ambient conditions:
Operating temperature range:-20 - +60°C
Relative humidity:90% (max., non-condensing)
Place of installation:potentially explosive area
Elektromágneses kompatibElectromagnetic compatibility (EMC)
accordance with the standard EN 61326-1
Immunity:industrial area
Noise emission:Group 1, Class B
General data:
Housing:moulded polycarbonate case; installable as a field or panelinstrument
Connection:IP 65 cable entry, screw terminal
Connection cable:0.25-1.5 mm2
Dimensions:167 × 87 × 95 mm (width × height × depth)
Weight:0.8 kg
Protection:IP 65
Detailed information see in operating instructions. The Manufacturer maintans the right to change the technical data!


Leaflet of productOperating InstructionATEX certificate

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