86
Unidrive M702 User Guide
Issue Number: 3
Common to all Feedback types
Sincos encoder resolution
The sine wave frequency can be up to 500 kHz but the resolution is
reduced at high frequency. Table 4-30 shows the number of bits of
interpolated information at different frequencies and with different
voltage levels at the drive encoder port. The total resolution in bits per
revolution is the ELPR plus the number of bits of interpolated
information. Although it is possible to obtain 11 bits of interpolation
information, the nominal design value is 10 bits.
Table 4-30 Feedback resolution based on frequency and voltage
level
4.16 SAFE TORQUE OFF (STO)
The SAFE TORQUE OFF function provides a means for preventing the
drive from generating torque in the motor, with a very high level of
integrity. It is suitable for incorporation into a safety system for a
machine. It is also suitable for use as a conventional drive enable input.
The safety function is active when either one or both STO inputs are in
the logic-low state as specified in the control terminal specification. The
function is defined according to EN 61800-5-2 and IEC 61800-5-2 as
follows. (In these standards a drive offering safety-related functions is
referred to as a PDS(SR)):
‘Power, that can cause rotation (or motion in the case of a linear motor),
is not applied to the motor. The PDS(SR) will not provide energy to the
motor which can generate torque (or force in the case of a linear motor)’.
This safety function corresponds to an uncontrolled stop in accordance
with stop category 0 of IEC 60204-1.
The SAFE TORQUE OFF function makes use of the special property of
an inverter drive with an induction motor, which is that torque cannot be
generated without the continuous correct active behavior of the inverter
circuit. All credible faults in the inverter power circuit cause a loss of
torque generation.
The SAFE TORQUE OFF function is fail-safe, so when the SAFE
TORQUE OFF input is disconnected the drive will not operate the motor,
even if a combination of components within the drive has failed. Most
component failures are revealed by the drive failing to operate. SAFE
TORQUE OFF is also independent of the drive firmware. This meets the
requirements of the following standards, for the prevention of operation
of the motor.
Data as verified by TÜV Rheinland:
According to EN ISO 13849-1:
PL = e
Category = 4
MTTF
D
= High
DC
av
= High
Mission Time and Proof Test Interval = 20 years
The calculated MTTF
D
for the complete STO function is:
STO1 2574 yr
STO2 2716 yr
According to EN 61800-5-2:
SIL = 3
PFH = 4.21 x 10
-11
h
-1
The SAFE TORQUE OFF input also meets the requirements of EN 81-1
(clause 12.7.3 b) as part of a system for preventing unwanted operation
of the motor in a lift (elevator).
SAFE TORQUE OFF can be used to eliminate electro-mechanical
contactors, including special safety contactors, which would otherwise
be required for safety applications.
11
W, Clock, Not used, Not used
12
W\, Clock\, Not used, Not used
AB Servo (3), FD Servo(4), FR Servo (5
),
SC Servo (12)
Type
EIA 485 differential receivers
Maximum input frequency
512 kHz
Line loading
Line termination components
120
Ω
(switchable)
Working common mode range
–7 V to +12 V
SC EnDat (9), SC SSI (11)
Type
Differential voltage
Maximum Signal level
1.25 V peak to peak (sin with
regard to sinref and cos with
regard to cosref)
Maximum input frequency
See
Maximum applied differential voltage and
common mode voltage range
±
4 V
EnDat (8), SSI (10), BiSS (13)
Not used
Resolver (14)
Not used
Common to All
Absolute maximum applied voltage relative to 0V -9 V to 14 V
13
Feedback device supply
Supply voltage
5.15 V ±2 %, 8 V ± 5 % or 15 V ± 5 %
Maximum output current
300 mA for 5 V and 8 V
200 mA for 15 V
The voltage on Terminal 13 is controlled by Pr
03.036
. The default for this
parameter is 5 V (0) but this can be set to 8 V (1) or 15 V (2). Setting the encoder
voltage too high for the encoder could result in damage to the feedback device.
The termination resistors should be disabled if the outputs from the encoder are
higher than 5 V.
14
0 V Common
15
Motor thermistor input
Thermistor type is selected in
P1 Thermistor Type
(03.118).
Volt/Freq
1 kHz
5 kHz
50 kHz 100 kHz 200 kHz 500 kHz
1.2
11
11
10
10
9
8
1.0
11
11
10
9
9
7
0.8
10
10
10
9
8
7
0.6
10
10
9
9
8
7
0.4
9
9
9
8
7
6
Summary of Contents for Unidrive M702
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