Functional Software description
DCS 500 Software Description
45
Tuning of Current
Regulator
Tuning of the regulator can be done either manually with response
tests or with autotuning function, which is activated by setting pa-
rameter
DRIVE MODE (1201)
to 3, when the drive’s main contactor
is open. After closing of the main contactor and starting of the
drive, the autotuning procedure for the armature current controller
will start. The DRIVE MODE (1201) value is set to 0 when auto-
tuning is completed. The autotuning proceeds without user inter-
vention. Motor data have to be set correctly before autotuning is
started. More information about tuning can be read in chapter
Start-up
.
Firing Angle
Limitation
The output signal of the regulator is the firing angle reference (1 =
1
°
)
ARM ALPHA (10401)
. Its minimum value is limited by means of
parameter:
The
maximum output voltage
of the thyristor bridge is limited by
parameter
ARM ALPHA LIM MIN (413),
default value =15
The armature voltage is U = 1.35 * U
SUPPLY
* Cos
α
, if the
current is continuous.
α
= ARM ALPHA.
For example, if U
SUPPLY
is 400 V AC, the maximum armature
voltage is 1.35 * 400 V * Cos 15
°
= 521 V.
The maximum firing angle is limited by parameter
ARM ALPHA LIM MAX (412),
default value = 150. Do not change
this value without consulting ABB!
Additional Com-
mutation Reserve
DXN
The commutation can not take place infinitely fast because of the
network reactance. The time for the commutation can be ex-
pressed by the commutation angle u, which can be calculated us-
ing formula:
u = arc cos (cos
α
- Id / Ik ) -
α
where Ik = short circuit current
Id = load current
Ul = network voltage
Xl = network total reactance
Example
It is wanted that a "weak" network can commutate 600 A current.
The nominal voltage of the network is 380 V and frequency 50 Hz.
Used transformer:
20 kV/400 V, 500 kVA
Rk = 0.0032
Ω
Lkm = 48.85
µ
H/phase
Cable: lenght 50 m, 250
µ
H/km, Lkk = 12.5
µ
H/phase
Содержание DCS 500B
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