Yokogawa DR240 - Manual (Page 87)

3-42 IM DR232-01E
Step 2 : Change the position of the noise source.
A) Leakage magnetic flux of transformer:
Φ = strong
Φ = weak
Move the instrument to a location
where the influence from magnetic
flux is weak.
B) Sparks
strong electromagnetic
radiation
weak electrogmagnetic
radiation
Move the instrument to a location
where the influence from electro-
magnetic radiation is weak.
spark
• Grounding: a decrease of impedance
The grounding method is the point of common mode noise suppression.
Equipment
under
measurement
(EUM) The instrument
ec ec'
EUM The instrument EUM The instrument
(if grounding is difficult)
or
The difference in the potential to the ground between EUM
and the instrument may cause a ground current, resulting in noise.
Equalize the potentials to the ground so
that the common mode noise becomes zero.
One-point grounding Potential equalization
The basic means to obtain stable measurement is to set the circuit potential with proper
grounding. Thus, potential equalization is the means to be adopted only when grounding is
impossible.
3.11 Countering Noise