ABB TTF300 Instrucciones Para La Puesta En Funcionamiento página 57

4.4 Shielding of the signal / power supply cable and the sensor connecting cable
To ensure the system benefits from optimum electromagnetic interference immunity, the
individual system components, and the connection cables in particular, need to be shielded.
The shield must be connected to the ground reference plane.
Important (Note)
National regulations and directives must be observed when grounding system components.
Notice - Potential damage to parts!
In systems without equipotential bonding or with potential differences between the individual
grounding points, multiple instances of shield grounding can result in transient currents at
system frequency.
These can damage the shielding and have a significant impact on signal transmission, of bus
signals in particular.
4.4.1 Examples of shielding / grounding
4.4.1.1 Insulated sensor measuring inset (thermocouple, mV, RTD, ohms), transmitter housing grounded
The shield of the sensor connecting cable is grounded via the grounded transmitter housing.
This shield is insulated from the sensor.
The shield of the power supply cable is grounded at the supply isolator / PCS input directly. This
shield is insulated from the transmitter housing.
The shields of the power supply cable and the sensor connecting cable must not be connected
to one another.
Make sure that the shields are not connected to ground anywhere else.
1
Fig. 9: Shields of the sensor connecting cable and the power supply cable are separate and each grounded at
one end
1 Temperature sensor
2 Shield insulated from sensor
3 Sensor connection cable
4 Shield grounded via transmitter housing
5 Transmitter housing, grounded
CI/TTF300-X1
2 3 4
5
6
6 Shield insulated from transmitter housing
7 Power supply cable
8 Grounding point
9 Supply isolator / PCS input
TTF300
Electrical connections
9
7
8
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