Encoder Initialisation; Encoder Power Supply Trips - Emerson unidrive sp User Manual
Universal variable speed ac drive for induction and servo motors
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- User manual (268 pages) ,
- User manual (310 pages) ,
- Technical note (6 pages)
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Parameter
Keypad and
Parameter
structure
display
x.00
Encoders
SC.EnDat, EnDat
SC.EnDat, EnDat
SC.Hiper, SC.EnDat, EnDat
SC.EnDat, EnDat
SC.Hiper, SC.EnDat, EnDat
+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. It should be noted that this system should not be used where 180 x Pr 5.11 (or Pr 21.11 for motor map 2) / Pr 3.34 is greater than
10° or else incorrect EnC3 trips will occur.
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 a Solutions 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.
Device
Ab, Fd, Fr, Ab.Servo,
Fd.Servo, Fr.Servo
SC,
SC.Hiper,
SC.EnData,
SC.SSI
SC.Hiper, SC.EnDat, EnDat Wire break in the comms link is detected by a CRC or timeout error.
SSI
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-initialized 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 initialisation 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:
Encoder type
Ab, Fd, Fr, Ab.Servo,
None
Fd.Servo, Fr.Servo
SC.Hiper
150ms, then encoder reset, then 150ms
SC.EnDat, EnDat
1.0s
All other types
1.2s
Encoder power supply trips
The encoder power supply from the drive can be switched off by the drive either because the encoder power supply is overloaded (Enc1 trip) or
because the internal 24V supply within the drive is overloaded (PS.24V trip). The internal 24V supply provides power for the encoder power supply,
user 24V output, digital I/O, Solutions Modules etc.
Unidrive SP Advanced User Guide
Issue Number: 10
Parameter
Advanced parameter
description format
descriptions
The number of encoder turns read from the encoder during auto-
configuration is not a power of 2
The number of bits defining the encoder position within a turn read from the
encoder during auto-configuration is too large.
The number of periods per revolution is either less than 1 or greater than
50000 when read or calculated from the encoder data during auto-
configuration.
The number of comms bits per period are larger than 255.
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.
Detection method
Hardware detectors on the A(F), B(D,R) and Z signal detect a wire
break.
The differential levels of the sine and cosine waveforms are
available to the drive. The drive detects wire break if Sine
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.
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.
Initialisation delay
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Serial comms
Macros
protocol
Reason for error
2
+Cosine
Electronic
Performance RFC mode
nameplate
Drive trip
Enc13
Enc14
Enc15
Enc 16
Enc 17
Drive Trip
Enc2
2
Enc2
Enc4, Enc5
Enc5, Enc6
Menu 3
All modes
75
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