Firing Angle Alpha In Degree - Siemens SINAMICS DCM 6RA80 Faq

Uvw: Line-to-line input voltage at converter, at 400 V: Udi = 540 V
Variable direct voltage Ud depending on firing angle:
Ud = Udi * cos , (in practical applications an additional voltage loss resulting from overlap o
also applies here; this is subtracted so that the resulting measured voltage is slightly lower
than that calculated)
: Firing angle in degrees, cos( ) can be read from the graph below to calculate the output
direct voltage.
Control characteristics for
Steuerkennlinie Drehstrombrückenschaltung
B2C, (B2)A(B2)C, B6C, (B6)A(B6)C
1
0,8
0,6
0,4
0,2
Rectifier operation
0
-0,2 0
-0,4
-0,6
-0,8
-1
For 3 phase application
Line current I1: I1[A] = Id[A]* root (2/3) = Id * 0.817, where Id: Direct Current
Current in thyristor: Iv [A]= Id * root (1/3) = Id * 0.58
Direct current power: P[W] = Ud[V] * Id
Active power Line: P = 1.05 * Ud * Id
Ideal current power:
Pdi[W] = Udi [V] * Id, use for peak power maximum direct current
Required apparent power of the line transformer:
S [VA]= Udi * 1.05 * Id
T
Phase control reactive power:
Q[Var] = 1.05 * Udi * Id * sin , at firing angle
cos in the line infeed: cos
cos is zero on motor speed zero,
at rated motor speed and rated motor voltage adjusted to the line voltage, it has the following
values: 2Q: 0.9; 4Q: 0,75.
Maximum output voltage for SINAMICS DCM at 5% undervoltage of the nominal line voltage:
2Q device: Ud = Uvw * 1.2;
max
Set p50101 as maximum to Ud
Note: The output voltage of the SINAMICS DCM depends on the voltage of the supply
system, not on the rated line-side voltage of the SINAMICS DCM.
The minimum permissible nominal line voltage (set p50078[0] nominal voltage for line)
is 50 V up to rated device voltage. For voltage range 10 – 50 V, order device with option L04.
(option L04 available for 400 / 460 / 575 V devices). Order L04 ex works, a retrofit involves a
lot of work.
Control characteristics for
B6C und (B6)A(B6)C
30 60

Firing angle Alpha in Degree

Steuerwinkel Alpha in Grad
= Ud / Udi
4Q device: Ud
max
Inverter operation
90 120
= Uvw * 1.05;
max
35
150 180