Rockwell Automation T8835 Trusted 60 Channel Analogue Input FTA Non Incendive - Manual (Page 7)

Trusted
TM
Analogue Input FTA Non Incendive T8835
Issue 1 Aug 08 PD-T8835 7
1. Description
The Trusted
TM
60 Channel Analogue Input FTA T8835 provides termination for a maximum of 60 input
channels from various types of field devices which generate an analogue signal. Figure 1 below shows
the configuration of a single channel.
Figure 1 Single Channel Schematic
The field supply is derived from dual 24V dc feeds which are ‘commoned’ via diodes on the FTA. The
supply is then fed to each channel.
The supply voltage to the field is fed via the 145R resistor. This effectively limits the current in the field
loop allowing inputs from nonincendive field devices located in hazardous areas. The incoming signal
from the field device is developed across the 250R resistor, then connected to the appropriate input
circuit on the Input Module. Electro-static discharge (ESD) transients are suppressed by D3.
The connector linking the 60 channels on the input module to the FTA is terminated at SK2 which is a
96-way socket. The SmartSlot connector is SK1 and is a 96-way socket (this socket is no longer
used). The dual 24V dc power supplies are connected to the FTA via a single 4-way connector (PL1).
Ten 12-way connectors are used for the field loops (PL2 to PL9, PL11 and PL12). PL10 is an auxiliary
2-way plug provided for power monitoring purposes (future use).
FIELD
TERMINATION
DUAL 24Vdc
FIELD
SUPPLIES
TO DUAL
DIGITAL INPUT
MODULE 8402
D3 250R
145R
REMAINING CHANNELS
0V