Connection Instructions For Earthed/Potential-Free Thermocouples - Beckhoff EL33-00 Series Documentation

Mounting and wiring
4.13.5 Connection instructions for earthed/potential-free
thermocouples
Due to the differential inputs of the terminals, different connection types are recommended depending on the
type of thermocouple used. For earthed thermocouples, ground is not connected to the shielding. If the
thermocouple does not have an ground connection, the ground and shielding contacts can be connected
(see Fig. Connection of earthed and earth-free thermocouples and Connection instructions for
thermocouples).
Connection instructions for thermocouples
• Earthed thermocouple
ð Do not connect GND to the shielding
ð For EL3312: potential difference max. 2 V
• Potential-free / earth-free thermocouple
ð GND can be connected to the shielding
ð or: GND can connected to any potential, max. 35 V to 0 V power
• Non-potential-free thermocouple
ð Do not connect GND to the shielding
ð Do not connect GND to thermocouple potential.
ð Thermocouple-potential max. 35 V to 0 V power
ð For different thermocouple potentials several 1-channel EL3311 units should be used.
• Unused inputs
ð For the multi-channel versions EL3312 and EL3314, unused inputs should be short-circuited
(low-resistance connection of +TC, -TC)
Fig. 55: Connection methods for earthed and earth-free thermocouples
The example shows EL3312. For the EL3314, the shield should be connected to an additional shield
terminal (EL9195).
70 Version: 4.2 EL33xx-00x0