Installation
Connection of the Logic Inputs
Two types of connection are possible:
z Direct connection for all information on logic inputs coming from the switchboard.
z Connection via interposing relays for all information on logic inputs coming from outside of the
switchboard and mainly connected with long lines.
Using interposing relays reduces EMC disturbance effects on the LTM R controller and improves the
reliability of the information.
Recommended Interposing Relay
Interposing relays must have the following characteristics:
z electromechanical relay with 2.5 kVAC isolation minimum
z self-cleaning or low level contact (I < 5 mA)
z installed in the switchboard as close as possible to the LTM R controller
z AC or DC control circuit voltage, supplied by separate power supply (not supplied by the same power
supply as the LTM R controller, to respect the galvanic isolation)
In case of long distances between the process and the LTM R controller, interposing relays with DC control
circuit voltage are recommended.
The protection module is mandatory on the interposing relays in order to suppress the surge.
The following Schneider Electric RSB1 interposing relays are recommended:
Reference Number
Control Circuit Voltage
Protection Module
RSB1A120•D
6, 12, 24, 48, 60, 110 VDC
Diode RZM040W
RSB1A120•7
24, 48 VAC
RC circuit RZM041BN7
RSB1A120•7
120, 220, 230, 240 VAC
RC circuit RZM041FU7
Use of DC Interposing Relays
The DC interposing relays are recommended because long wires distances can be used to command the
relay.
DC RSB1 relay voltage
24 VDC
48 VDC
110 VDC
Maximum distance for wires in parallel
without metallic screening
3,000 m (10,000 ft)
3,000 m (10,000 ft)
3,000 m (10,000 ft)
Maximum distance for wires in parallel with 3,000 m (10,000 ft)
metallic screening
3,000 m (10,000 ft)
3,000 m (10,000 ft)
The following diagram shows an example when using DC interposing relays:
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1639502EN-04 09/2014