Configuration Example 3 - ABB RER670 Applications Manual

Section 4
Analog inputs
4.2.5.3
62
1. Connect UL1L2 voltage to the third input of the SMAI
2. Connect one not used and externally not wired VT input on the RER670 TRM,
with set ratio as 0.1kV/100V=1.00, to the fourth input of the SMAI function
block. This in principle gives zero value for 2Uo quantity.
3. Note that, in a rear case that 2Uo voltage is available from the two-phase
power system then just simply connect it to the second VT input on the TRM
and set its ratio accordingly. In such cases, all internal calculations will work
correctly all the time.
When such configuration is made within ACT tool using three available analogue
signals (i.e. UL1L2, IL1 and IL2), the preprocessing block will perform the
following:
• Quantities for the first phase and second phase currents (i.e. IL1 and IL2) will
be directly measured from the TRM
• Quantities for the first phase and second phase voltages (i.e. UL1 and UL2)
will be calculated. Because by such arrangement, the 2Uo is practically forced
to zero, the two phase voltages will be calculated correctly only during
symmetrical operating condition in the network (i.e. without any earth fault)
using the following formulas UL1 = -UL2 = UL1L2/2
• Phase-to-phase current value (i.e. IL1L2 = (IL1-IL2) ) will be internally
calculated
• Phase-to-phase voltage value (i.e. UL1L2 ) will be directly measured from the
TRM
• Positive sequence quantities (i.e. U1 = (UL1-UL2)/2 and I1 = (IL1-IL2)/2 )
will be internally calculated
• Zero sequence current quantity (i.e. 2Io = (IL1+IL2) ) will be internally
calculated.
• Zero sequence voltage quantity (i.e. 2Uo ) will be directly measured from the
TRM. However, because this input is not wired and the ratio is set to value
one, it will practically be forced to zero value permanently.
Note that in such installations, distance or under-impedance protection can only use
L1-L2 measurement loop which will then effectively measure impedance Z =
UL1L2/(IL1-IL2). The directional overcurrent protection can also be used.
Directional earth fault protection and residual overvoltage protection shall not be
used in such installations. All other backup protection and measurement functions
can be used.

Configuration example 3

An example on how to configure the IED analogue inputs for single-phase railway
supply systems or BT-catenary railway supply systems is shown in Figure 21.
1MRK 506 375-UEN A
GUID-09488ED6-BABD-4BCE-B4F2-F5539100308E v1
Railway application RER670 2.2 IEC
Application manual