Famco MONT72 Series, User Manual

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Chapter 4 Electrical Installation Shenzhen Hpmont Technology Co., Ltd.
- 32 - MONT72 Series User Manual V1.0
4.6.4 Ground Connection
The grounding terminals PE must be connected to ground properly. The grounding cable should be as
short as possible (the grounding point should be as close to the controller as possible) and the
grounding area should be as large as possible. The grounding resistance should be less than 10Ω.
Do not share the grounding wire with other devices (A). MONT72 can share grounding pole with other
devices (C). It achieves the best effect if MONT72 and other devices use dedicated grounding poles (B),
as shown in Figure 4-21.
Figure 4-21 Grounding method
When using more than one controller, be careful not to loop the ground wire as shown in Figure 4-22.
Figure 4-22 Prohibited grounding method
4.6.5 EMI Filter
The EMI filter should be used in the equipment that may generate strong EMI or the equipment that is
sensitive to the external EMI. The EMI filter is a dual-way low pass filter through which lower frequency
current can flow while higher frequency current can hardly flow.
Function of EMI filter
1. The EMI filter ensures the equipment not only satisfy the conducting emission and conducting
sensitivity in EMC standard but also can suppress the radiation of the equipment.
2. It can prevent the EMI generated by equipment from entering the power cable and the EMI
generated by power cable from entering equipment.
Common mistakes in using EMI filter
Common mistakes in using EMI filter
1 Too long the power cable is between the EMI filter and the controller
The filter inside the cabinet should be located near to the input power source. The length of the power
cables should be as short as possible.
2
Too close the input and output cables of the EMI filter
The distance between input and output cables of the filter should be as far apart as possible. Otherwise the
high-frequency noise may be coupled between the cables and bypass the filter. Thus, the filter will become
ineffective.
3 Bad grounding of the EMI filter
The enclosure of EMI filter must be grounded properly to the metal case of the controller. In order to achieve
better grounding effect, make use of a special grounding terminal on the enclosure. If using one cable to
connect the filter to the case, the grounding is useless for high frequency interference. When the frequency
is high, so is the impedance of cable, hence there is little bypass effect.
Controller Other Controller
PE PE
A. Sharing grounding wire
PE PE
B. Dedicated grounding pole
PE PE
C. Sharing grounding pole
Other Controller Other
Controller Controller Controller Controller
PE PE PE PE
Prohibited grounding method