Computing Phase Current On The Mains - REXROTH EcoDrive Cs Project Planning Manual

Rexroth EcoDrive Cs Drives

Computing Phase Current on the Mains

DOK-ECODR3-DKC**.3-CS*-PR02-EN-P
To select a suitable mains contactor and fuses for the power connections
it is necessary to first compute the phase current I
The mains-side phase current I
connecting power S .
N1
Selecting the mains connecting power in the list or compute it according
to the following formula. With multiple controllers, add the individual
powers.
The mains connecting power can be determined
•
by selecting the mains connecting power in the list resp. the technical
data
- or -
•
by computing it according to the following formula.
Note : With multiple controllers, add the individual powers and, if
necessary, take a coincidence factor into account, because
often not all servo axes require full power simultaneously.
P
ZWD
P : required DC bus continuous power in W
ZWD
M : rms torque in Nm
EFF
n : mean speed in min-1
MITTEL
k: factor for motor and controller efficiency
Fig. 6-13: Computing DC bus power
S : connected load in VA
N1
P : DC bus continuous power in W
ZWD
F: connected load factor due to the non-sinusoidal phase current
Fig. 6-14: Computing mains connected load
Single-phase load:
Three-phase load:
I : mains-side phase current in A
N1
S : connected load in VA
N1
U : voltage between phases of the mains in V
N1
Fig. 6-15: Computing mains-side phase current
Mains and Supply Voltage Connection
at the mains.
N
is determined out of the mains
N1
⋅ ⋅ ⋅ π
M n 2
EFF MITTEL k ⋅
=
60
⋅
S = P F
N1 ZWD
I =
N1
I =
N1
U
N1
6-11
S
N1
U
N1
S
N1
⋅
3