User's Manual

Doc.: HD0389-00-Manuale_TL_GWCxxxx_r.0.1_EN.doc-00 17/04/2011 Page 48 of 49
A.2 Power supply
Connection diagram
Surge
suppressors On transformer primary circuit, they protect device from mains surge.
Transformer
Transformer primary circuit have to be chosen according to mains
characteristics. Voltage peaks on secondary are equals to
V
2-RMS
 2
where V
2-RMS
is transformer secondary circuit nominal voltage
Power supply characteristics depend upon loads connected to DC
line.
Approx. characteristics can be obtained applying the following
procedure:
• Overall power consumption P
tot
(Watt):
P
tot
= P
L
Where P
L
is a connected load power consumption in Watt.
• Transformer power P
Tr
(Watt):
P
Tr
= 2 P
tot
• Transformer power P
TrVA
(VA):
P
TrVA
= P
Tr
/ 0.7 (1 ph.)
P
TrVA
= P
Tr
/ 0.8 (3 ph.)
• Let consider a voltage fall equals to 8% of nominal voltage
on load connection, then:
P
TrVA
= V
dcBUS
 I
max
 2
Transformer
M
a
i
n
s
Protections
EMC filter
~ +
~
-
Twisted
Surge
suppressors
C
Discharge
resistor