Bypass Scr Short-Circuit Detection - Tripp Lite SU60KX Manual

2 Theory of Operation (continued)

2.8 Bypass SCR Short-Circuit Detection

Located at NH-SYS-FB board (Circuit for Bypass Back-Feed Detect)
R
S
T
N
Located at NH-SYS-P board (Auxiliary Power for System, Detect Circuit for Voltage and Current)
Located at NH-SYS-M board (System MCU and Control Circuit)
(a) During backup mode, bypass 3 SCRs should be off and zero current should be running through CTFB1, CTFB2 and CTFB3. If current is
running through CTFB1, CTFB2 or CTFB3, then STShort_R (5), STShort_S (129) or STShort_T (128) will be low. The UPS will turn off its
inverter to prevent back-feed voltage.
CTFB1
CFA22 SCCT_R+
CFB18
CTFB2
CFA18 SCCT_S+
CNFB13
CFB19
1 BKFD_R
2 BKFD_S
3 BKFD_T
4
CTFB3
CFA12 SCCT_T+
CFB20
+12VS
CP63
RP34 RP33
-12VS
UP18A
2
BKFD_R 3
CP64
+12VS
CP62
RP86
+12VS
RP87
RP88
-12VS
UP20A
2
BKFD_S
3
+12VS
CP67
CP85
RP98
+12VS
RP103
RP104 -12VS
UP17A
2
BKFD_T
3
+12VS
CP70
RP117
CP75
RM 48 RM 56
RM 52
5VS 5VS
SCRST_R STShort_R SCRST_S
(5)
CM 26
G1
RFB1
BKFD_R
QFB1
RFB2
DFB1
RFB7
RFB3
BKFD_S
QFB2
RFB4
DFB2
RFB8
RFB5
BKFD_T
QFB3
RFB6
DFB3
RFB9
G1
DP13
RP35
1
QP13
RP37
CP65
RP38
G1
G1
CP84
G1
DP15
RP89
1
QP15
RP92
CP68
RP93
G1
G1
CP74
G1
DP46
RP105
1
QP17
RP111
CP71
RP112
G1
G1
RM 65
RM 57 RM 66
5VS
STShort_S SCRST_T
(129)
CM 29 CM 33
G1 G1
56
SCRST_R
SCRST_S
SCRST_T
STShort_T
(128)