Service manual

The low voltage power supplies are activated when the DC
bus reaches approximately 50 V DC less than the alarm
voltage low for the DC bus (see rating tables in
1 Introduction). After a short delay, an inrush enable signal
is sent from the control card to the power card SCR gating
circuit. The SCRs are automatically gated when forward
biased, as a result acting similar to an uncontrolled
rectifier.
When the DC bus capacitors are fully charged, the voltage
on the DC bus is equal to the peak voltage of the input AC
line. Theoretically, this can be calculated by multiplying the
AC line value by 1.414 (V ACx1.414). However, since AC
ripple voltage is present on the DC bus, the actual DC
value is closer to V ACx1.38 under unloaded conditions
and may drop to V ACx1.32 while running under load. For
example, a frequency converter connected to a nominal
460 V line, while sitting idle, the DC bus voltage is approxi-
mately 635 V DC (460x1.38).
As long as power is applied to the frequency converter,
this voltage is present in the intermediate circuit and the
inverter circuit. It is also fed to the Switch Mode Power
Supply (SMPS) on the power card and is used for
generating all other low voltage supplies.
x 3
DC /
AC
o
C
Temp
.
conv.
uC+
EEP
7
xGD
RL 1
GD
Supply
A
BR
GD
BR
FB
INV
GD
AC
/
DC
x3
BR
P_BRF
RL 2
RFI _ RL 1
Inrush
SAFE
_
FB
Tmp
_
VGDS
VCC
FAN
1
CAN
A
A
Imax2
comp
.
MAINS
RL 2 RL 1
RFI
(variations)
Tmp
_
VGDS
L1
L2
L3
Inrush
RFI
_
RL 2
RFI
_
RL 1
FFB 1
Int.
fans
”Internal supply bus”
”Internal Communication”
Level
Shift
VCX (GX) 5V
VCC (GND) 5V
VDD (GND) 24V
SMPS
Motor
U
V
W
UINV_P
UINV_N
VGD +/- 15
/
UDC -/-5
VGD +/- 15/UDC -/-5
RFI
_
RL 2
Control Card
ACP
Isol. RS 485
D-I /O
A-I/O
MCP
LCP
Display
control
panel
Brake not connected to terminal on FC
101
130BC134.10
Illustration 3.3 Example of H6 Power and Control Section
Internal Frequency Converte...
VLT
®
HVAC Basic Drive Service Manual
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®
is a registered Danfoss trademark 25
3
3