Siemens SENTRON - Page 212

Applications
13.4 Transfer between three sources with two outgoing loads
212 Manual, 08/2017, L1V30368969104A-02
Transfer with T1 (kVA) < T2 (kVA) and T2 (kVA) > T3 (kVA)
As well as the previously described applications, applications comprising 3 transformers (T1,
T2, T3) where the power of the transformer T2 is greater than that of the other two
(T1 (kVA) < T2 (kVA) and T2 (kVA) > T3 (kVA)) can also be implemented with the transfer
switching equipment. By using two transfer switches, this complex application can be
realized, thus enabling the power supply to be maintained.
Figure 13-7 Transfer T1 (kVA) < T2 (kVA) and T2 (kVA) > T3 (kVA)
T1
T2
T3
Switching state
of the transfer
switching
equipment
Non-critical
load 1
Critical
load 2
0 0 0 x OFF OFF
1 0 0 P1 ON OFF
0 1 0 P2 + P3 ON ON
0 0 1 P4 OFF ON
1 0 1 P1 + P4 ON ON
0 1 1 P2
+ (P3 or P4)*
ON ON
1 1 0 (P1 or P2)*
+ P3
ON ON
1 1 1 (P1 or P2)*
+ (P3 or P4)*
ON ON
* Dependent on the priority setting on the transfer switching equipment