MEDTEQ Mini-CMRR Test Box

Please note: As of January 1, 2014,  sales of ECG related equipment (SECG, MECG, CMRR, ECG set) are being handled by Whaleteq in Taiwan. Please contact Mr. Nathan Lin for pricing and delivery schedule (nathan.lin@whaleteq.com). This page is retained for reference only. 

ECG related standards such as IEC 60601-2-27, IEC 60601-2-47 and IEC 60601-2-51 require a common mode rejection ratio test (CMRR) utilising the double box construction as described in each standard (all standards are the same).

MEDTEQ's Mini-CMRR Box 2.0 follows the requirements of the standard, but includes a number of convenient features such as: 

  • precision internal dc offset (+/-300mV, adjustment not needed)
     
  • internal ~1:3 transformer allowing a normal function generator to supply the required 20Vrms1
     
  • internal 50MΩ 1000:1 divider to allow direct monitoring of the common mode voltage (10Vrms)2 

     

The construction construction has been simplified by eliminating switches in the standard as follows. As the switching varies by standard, two boxes are avaliable to cover all standards:

Model Standards Details
Mini-CMRR 2.0 IEC 60601-2-27
IEC 60601-2-51
  • Only RA has the imbalance impedance (51k/47nF)
  • User can test each lead electrode by swappling leads to the RA terminal in turn
  • Compatible with the ECG breakout box used for MEDTEQ SECG, MECG systems
Mini-CMRR 2.0A IEC 60601-2-47
ANSI/AAMI EC 13

 

  • All leads RA ~ V6 have 51k/47nF impedance
  • Two additional terminals provided:
    • Imbalance terminal (no impedance) with switchable DC offset
    • Imbalance terminal (no impedance) without switchable DC offset
  • Requires special breakout box

  

1Most function generators are limited to 7Vrms, thus a step up transformer is needed

2Due to the high impedance of the internal 100pF capacitors at mains frequency (around 30MΩ), normal multimeters cannot be used to measure the applied voltage. A 50MΩ 1000:1 divider has been found to be the best compromise for accuracy and impact to the test.

See the Test Equipment Overview page for links to instruction manuals and pricing, or contact MEDTEQ for more information (equipment@medteq.info or peter.selvey@medteq.jp)