Kl3228 - Positioning Within The Bus Terminal Block; Fig. 14 Kl3228/Kl9187 - Example For Bad Positioning - Beckhoff KL3208 Manual

3.5

KL3228 - Positioning within the Bus Terminal Block

Connect the back wires of the eight PT sensors via a potential distribution terminal (KL9187). The KL9187
leads the back wires via Power Contact (0 V) back to the KL3228.
Mount the KL3228/KL9187 directly before the KL9010 bus end terminal
Mount the KL3228/KL9187 directly adjacent to each other and as far to the right as possible in the
Bus Terminal block, ideally directly before the KL9010 bus end terminal!
If further Bus Terminals that draw current from the power contacts are mounted to the right of the
KL3228/KL9187 in the Bus Terminal block, this current will lead to a voltage drop on the power con-
tacts between KL3228 and KL9187. This voltage drop can falsify the measured values of the
KL3228, since the back wires of the PT sensors are also routed via the power contact (0 V).
Example for bad positioning
This example shows the KL3228/KL9187 mounted on the left in the Bus Terminal Block. There are big
current consumers mounted to the right side of KL3228/KL9187.
Fig. 14: KL3228/KL9187 - Example for bad positioning
The KL2442 drives a current of 4 A through each of the two load resistors R1 and R2.
This current (8 A in total) must flow back to the power supply unit via the power contacts
and causes the voltage drop U
The KL3228 drives a current through the sensor S1.
This current similarly flows back to the KL3228 via the power contact marked in yellow.
The voltage drop U thus causes a measuring error during the resistance measurement by the KL3228.
PC
KL3208, KL3228/KS3228
on the power contact marked in yellow (between KL3228 and KL9187).
PC
Version: 3.3.0
Mounting and wiring
25