VariTrans A 21000

Isolated Standard Signal Conditioner

The first standard-signal isolation amplifier with broad-range power supply in the 6-mm class.

The VariTrans A 21000 isolates, transmits and converts 0 to 20/4 to 20 mA and 0 to 10 V with a high level of accuracy. In spite of its modular housing being only 6 mm wide, the new VariTrans isolation amplifier provides maximum protection of personnel and equipment through protective separation up to a working voltage of 300 V conforming to EN 61140. The test voltage is 2.5 kV AC. It can be supplied with either 24 V DC or 230 V AC.


  • Broad-range power supply
    24 to 110 V DC (+/-25 %) and 110 to 230 V AC (+/-10 %)
  • Standards-compliant personal and plant protection
    Protective separation according to EN 61140
  • 3-port isolation
    Prevention of incorrect measurements caused by potential differences
  • Ideal value for money
    High accuracy and isolation – 2.5 kV AC test voltage
  • Easy installation
    DIN rail bus connectors allow for easy and extremely cost efficient connection of the power supply to several VariTrans A 21000 or other Knick products in 6 mm housings.
  • Cost reduction with smaller enclosure
    More channels per meter DIN rail thanks to space-saving 6 mm housing and closely packed mounting
  • Long service life
    Extremely low failure rate  (MTBF of 280 years) due to reduced self-heating
  • High accuracy and temperature stability
    Gain error 0.2 % and temperature coefficient 0.01 %/K
  • Calibrated range selection
    without complicated readjustments
  • Easy configuration
    DIP switch accessible from outside
  • Adjustable or fixed-range models
  • International use
    UL approvals for US and Canada
  • 5-year warranty

The Task
Isolation and conversion of 0 … 20 mA, 4 … 20 mA and 0 … 10 V standard signals with high measurement accuracy requirements. At the same time, best possible protection of personnel and equipment must be guaranteed.

The Problem
The standards governing the erection of installations demand protective separation according to EN 61140. The tightly dimensioned installation space on the mounting rail must be optimally used.
Procurement logistics and stockkeeping demand a universal product which covers all common signal combinations and which can be used around the world with the broad-range power supply.

The Solution
In spite of the just 6 mm wide modular housing, VariTrans A 21000 meets the requirements of EN 61140 regarding protective separation up to an operating voltage of 300 V. The test voltage is 2.5 kV AC.
Very small leakage capacitances also ensure that high transient common-mode interferences can be isolated reliably and don’t lead to system malfunctions. Standardization and flexible signal conversion are optimally implemented by the calibrated range selection – on-site calibration becomes superfluous.






Product Catalog (en)

13148 |  Interface Technology | ProLine
Product Description | Specifications | Product Range
PDF (file size: 15.98 MB)

Catalog Excerpts

Catalog Excerpt (en)

370 |  VariTrans A 21000
Product Description | Specifications | Product Range
PDF (file size: 0.9 MB)


Manual (en)

375 |  VariTrans A 21000
PDF (file size: 0.57 MB)

Manual (en)

13391 |  ZU 0677 (Power terminal block)
PDF (file size: 0.22 MB)

Certificates / Approvals

EC Declaration of Conformity (en)

11493 |  Series VariTrans A 21000 P0
Document No. EG110404A | 2011-04-04    
PDF (file size: 0.52 MB)

TR Declaration EAC (en)

12727 |  ProLine Devices
PDF (file size: 1.31 MB)