CMRR 3.0E | User Manual
5
1
Introduction
CMRR 3.0E uses double shielding construction according to IEC80601-2-26:2019 standard and includes
the following features
-
Built-in sine wave signal generator. CMRR 3.0E provides 2 Vrms signal output required by
IEC80601-2-26:2019 and the frequencies covers 50 Hz, 60 Hz, 100 Hz, and 120Hz.
-
Use coarse and fine knobs to adjust the variable capacitance value Ct. The sum of Ct and Cx (stray
capacitance) shall be 100pF.
-
Built-in voltage measuring circuit for Vs and Vc voltages. Vs value indicates the signal voltage
generated by built-in sine wave generator and Vc value is the voltage behind 100 pF capacitive
voltage divider.
User can easily confirm whether Vc value is half of Vs value while adjusting
capacitor value Ct.
-
Offer a precise and stable ± 150mV DC power supply.
-
Provide imbalance impendence and DC offset options. Use MCU to control relay to switch on and
off within the isolated circuit.
-
Provide output terminals of Vs, Vc, Monitor and GND for monitoring applied voltages in the
calibration process. For Monitor output terminal, it’s designed to confirm voltage value Vc. Due
to the high impedance brought by 100 pF at 50/60/100/120hz, this causes typical multimeters
being not able to measure precisely. Besides, it requires non-load output voltage at 10 Vrms in
certain IEC standards. Therefore, WhaleTeq CMRR 3.0E uses 11:1 (110M
Ω
：
10MΩ
）
voltage
divider and designated circuit design as the best compromise solution for accuracy, circuit load,
noise and input impedance of typical multimeters. Therefore, the Monitor terminal voltage shall
be Vc/11 Vrms.
-
CMRR 3.0E is equipped with a touch screen which enables to adjust and display all required test
parameters on the screen.
-
Via USB interface connection, CMRR 3.0E can be controlled by PC software or SDK (Software
Development Kit).
-
CMRR Standard Assistant software simplifies medical standards with test procedures, test options
and pass criteria. User can easily select and click to conduct the required tests.
2
Electrical Diagram
Figure 2-1 indicates the electrical diagram of CMRR 3.0E. Ct is the adjustable variable capacitance and Cx
is the stray capacitance between inner shield and outer shield.
