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68 Unidrive SP Advanced User Guide
www.controltechniques.com Issue Number: 7
+These trips can be enabled/disabled by Pr 3.40
1. If the terminations are not enabled on the A, B or Z inputs the wire break system will not operate. (Note that as default the Z input terminations
are disabled to disable wire break detection on this input.)
2. Phase error for a servo type encoder is to detect that the incremental pulses have been counted incorrectly. The error is detected if the
incremental position moves by 10° with respect to the position defined by the UVW commutation signals. The trip is initiated if the error is
detected for 10 consecutive samples.
3. Phase error for SinCos encoders with comms is detected by interrogating the encoder every second via comms to compare the incremental
position determined from the sine waves with the incremental position via comms. If the error is greater than 10° for 10 consecutive samples the
trip is initiated.
4. Incorrect encoder phasing is detected if the motor reaches half of the speed defined by SPEED_FREQ_MAX and the phasing error is larger
enough for the motor to accelerate uncontrollably. It can be disabled by setting Pr 3.08 to any value greater than zero.
5. This trip can also be caused when data is transferred between the encoder and an option module, such as an SM-Applications module, and an
error other than those covered by Enc5 or Enc6 occurs.
Wire-break detection
It may be important to detect a break in the connections between the drive and the position feedback device. This feature is provided for most
encoder types either directly or indirectly as listed below.
Encoder initialisation
Encoder initialisation will occur as follows: at drive power-up, when requested by the user via Pr 3.47, when trips PS.24V or Enc1 to Enc8 or Enc11 to
Enc17 are reset. Initialisation causes an encoder with comms to be re-initialised and auto-configuration to be performed if selected. After initialisation
Ab.Servo, Fd.Servo and Fr.Servo encoders will use the UVW commutations signals to give position feedback for the first 120deg (electrical) of
rotation when the motor is restarted.
A delay is provided during intialisation for some encoders to allow the encoder to be ready to provide position information after it has powered up. The
delay is provided during initialisation because this occurs during drive power-up and after encoder power supply trips are reset. The delays are as
follows:
SC, SC.Hiper, SC.EnDat,
SC.SSI, EnDat, SSI
Initialisation has failed due to a comms error. Enc7
SC.Hiper, SC.EnDat, EnDat
Auto-configuration has been requested by changing Pr 3.41, but
an initialisation has not occurred to perform auto-configuration.
Enc8
All
Speed feedback selected from an option slot that does not have
a position feedback category option module fitted
Enc9
All (Servo mode only)
Incorrect encoder phasing
(4)
Enc10
SC, SC.Hiper, SC.EnDat, SC.SSI Failure of Analog position alignment during encoder initialisation Enc11
SC.Hiper
The encoder type could not be identified during auto-
configuration
Enc12
SC.EnDat, EnDat
The number of encoder turns read from the encoder during
auto-configuration is not a power of 2
Enc13
SC.EnDat, EnDat
The number of bits defining the encoder position within a turn
read from the encoder during auto-configuration is too large.
Enc14
SC.Hiper, SC.EnDat, EnDat
The number of periods per revolution is either less than 2 or
greater than 50000 when read or calculated from the encoder
data during auto-configuration.
Enc15
SC.EnDat, EnDat The number of comms bits per period are larger than 255. Enc 16
SC.Hiper, SC.EnDat, EnDat
This is a rotary encoder (Pr 3.39=1 or 2) and the lines per
revolution read from this encoder are not a power of two.
Enc 17
Device Detection method Drive Trip
Ab, Fd, Fr, Ab.Servo,
Fd.Servo, Fr.Servo
Hardware detectors on the A(F), B(D,R) and Z signal detect a wire
break.
Enc2
SC,
SC.Hiper,
SC.EnData,
SC.SSI
The differential levels of the sine and cosine waveforms are
available to the drive. The drive detects wire break if Sine
2
+Cosine
2
is less than the value produced by two valid waveforms with a
differential peak to peak magnitude of 0.25V (1/4 of the nominal
level). This detects wire break in the sine and cosine connections.
Enc2
SC.Hiper, SC.EnDat, EnDat Wire break in the comms link is detected by a CRC or timeout error. Enc4, Enc5
SSI
Wire break detection is difficult with these devices. However, if
power supply monitoring is enabled the drive will be looking for a
one at the start of the message and a zero to indicate that the power
supply is okay. If the clock stops or the data line is disconnected the
data input to the drive may stay in one state or the other and cause a
trip.
Enc5, Enc6
Encoders Reason for error Drive trip
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