User guide

MODEL 3629C 17 04/10/2007
POWER CONNECTIONS (Continued)
FUSES
LINE 1
LINE 2
LINE 3
LOAD 1
LOAD 2
LOAD 3
TO
3 PHASE SUPP
LY
A
B
C
4 WIRE WYE LOAD
DELTA - 4 WIRE
WYE XFRMR
X
X
1 2
C
LOSED
Mode Switch
See Adjustments
Section
Note: It is recommended that the load and controller be protected by 3 class
"T" or "Semiconductor” fuses. Choose a fuse size approximately 120 to
125% of the current rating of the controller.
DELTA-WYE TRANSFORMER - With WYE load
Using a Delta primary to a 3 wire Wye secondary transformer into a wye load with an SCR
controller is not recommended. If the load across any two legs would happen to open, the
high voltages induced across the primary would almost certainly cause the SCR's to fail.
Using a fourth wire, to connect the junction of the secondary Wye to the junction of the Wye
load, would eliminate this problem.
See Replacement Parts sections.
Figure 27. In-line connections to delta-wye transformer coupled 4 wire wye load.
X
X
1 2
C
LOSED
Mode Switch
DELTA-WYE TRANSFORMER - With DELTA load
Applying a Delta load to the Wye secondary would be less likely to create the same problem,
as two loads would have to open to induce high voltages across the primary.
DELTA L
OAD
DELTA WIRE
WYE XFRMR
FUSES
LINE 1
LINE 2
LINE 3
LOAD 1
LOAD 2
LOAD 3
TO 3 PHASE SUPP
LY
A
B
C
See Adjustments
Section
Figure 28. In-line connections to a delta-wye transformer couple delta load.