ABB DCS550 - Page 231

231
Signal and parameter list
3ADW000379R0501 DCS550 Manual e e
Signal / Parameter name
min.
max.
def.
unit
50.03 M1SpeedFbSel (speed feedback selector)
Speed feedback selection:
0 =
EMF speed is calculated by means of the EMF feedback with flux compensation, default
1 =
Encoder speed is measured by means of a pulse encoder
2 =
Tacho speed is measured by means of an analog tacho
3 =
External MotSpeed (1.04) is updated by Adaptive Program or overriding control
Notes:
−
It is not possible to go into field weakening range when M1SpeeFbSel (50.03) = EMF.
−
When using EMF speed feedback together with a DC-breaker wrong voltage measurements can lead to
F532 MotOverSpeed [FaultWord2 (9.02) bit 15]. In case of an open DC-
breaker the voltage measurement
might show high values caused by leakage currents through the snubber circuits of the thyristors, because
there is no load on the DC side. To prevent these trips set MainContAck (10.21) = DCcontact.
Int. Scaling: 1 == 1 Type: C Volatile: N
EMF
External
EMF
-
50.04 M1EncPulseNo (encoder 1 pulse number)
Amount of pulses per revolution (ppr) for the pulse encoder.
Int. Scaling: 1 == 1 ppr Type: I Volatile: N
20
10000
1024
ppr
50.05 MaxEncoderTime (maximum encoder time)
When an encoder is used as speed feedback device the actual speed is measured by counting the amount of
pulses per cycle time. The cycle time for the measurement is synchronized with
the mains (every 3.3 ms or
2.77 ms).
In case very small speeds have to be measured
- that means there is less than one pulse per cycle time - it is
possible to increase the measuring time by means of
MaxEncoderTime (50.05)
. The speed is set to zero after
MaxEncoderTime (50.05)
is elapsed without a measured pulse.
Notes:
−
Formula to calculate the maximum speed using an encoder:
[ ]
ppr
skHz
rpmn
60*300
max
=
with: ppr = pulses per revolution - see M1EncPulseNo (50.04)
−
Formula to calculate the minimum speed resolution using an encoder:
[ ]
cycle
tpprk
s
rpmn
**
60
min
=
with: k = 4 (speed evaluation factor)
ppr = pulses per revolution - see M1EncPulseNo (50.04)
t
cycle
= cycle time of the speed controller, either 3.3 ms or 2.77 ms
Int. Scaling: 1 == 1 ms Type: I Volatile: N
3
200
3
ms