mattke MTR 5K Parts list manual

TECHNICAL DESCRIPTION
Edition 1.00
4-QUADRANT-SERVO-AMPLIFIER
TYPE
MTR 5
MTR 20
Telefon: [phone]
Telefax: [phone]
E-Mail: [email protected]
http://www.mattke.de
MATT E AG
Leinenweberstraße 12
D-79108 Freiburg
Germany

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 2
Dear customer,
We always try to guarantee for an optimum of security measures and to inform our-
selves about the latest developments in technical research. However, it is necessary
that we pass on the following further information to you as the user of our compo-
nents:
The appliances are supply parts meant for processing by industry, trade or other fac-
tories specialized in electronics.
Safety precaution !!
Attention - do not touch! The appliances have unprotected live parts. The voltage
may be highly dangerous.
We also have to inform you that, for your own security, only an expert should work on
the appliances.
In order to comply with the safety precautions, open connections must be protected
against contact with cases, coverings or anything similar. Even after the appliance
had been disconnected, there may still be a dangerous voltage (discharges of the
capacitors).
Due to an error in handling or unfavorable conditions, the electrolytic capacitors may
explode. If you have to work on the open appliance, do protect your body (hands!)
and your face!
Make sure that there is enough ventilation because of the fire risk in case of over-
heating.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 3
Table of Contents
TECHNICAL DESCRIPTION....................................................................................................................1
Edition 1.00 ...........................................................................................................................................1
1. Technical Description ....................................................................................................................5
1.1 General Information ...................................................................................................................5
1.2 Special Features ........................................................................................................................5
1.3 Summary of Types.....................................................................................................................6
1.4 Technical Data ...........................................................................................................................7
1.5 Functional Principles and Basic Circuit Diagrams ...................................................................10
1.5.1 Free Nominal Voltage Choice...........................................................................................10
1.5.2 Auxiliary Voltage ...............................................................................................................11
1.5.3 Function Principles of the Output Stage ...........................................................................11
1.5.4 Electrical Isolation .............................................................................................................14
1.5.5 Limit Switch Input with Automatic Braking........................................................................15
1.5.6 Blocking Protection ...........................................................................................................15
1.6 Overview of Terminals .............................................................................................................15
2. Projecting and Dimensioning.......................................................................................................19
2.1 Load Category..........................................................................................................................19
2.2 Optimizing the Drive for Given Amplifier Power.......................................................................20
2.3 Determination of the RMS Current for Dynamic Load .............................................................20
2.4 Nominal Voltage.......................................................................................................................22
2.5 Mains Transformer Calculation ................................................................................................23
2.6 Ballast Resistor ........................................................................................................................24
2.7 Commutation Current Limiting .................................................................................................25
2.8 Dynamic Brake (Option)...........................................................................................................26
2.9 Ramp Generator (Option, external) .........................................................................................27
2.10 Fuse Protection for Principal Power Supply ............................................................................27
2.11 Multiple Shaft Operation ..........................................................................................................28
2.12 Electrical Installation, Grounding, Erection ..............................................................................30
3. Commissioning and Operation ....................................................................................................34
3.1 Potentiometers, Fixed Components and Test Points (Overview)............................................34
3.2 Presetting .................................................................................................................................37
3.3 Correct Polarities......................................................................................................................37
3.4 Commissioning (First-Time Switch-On) ...................................................................................37
3.5 Current Adjustment ..................................................................................................................38
3.6 Tacho-Voltage..........................................................................................................................38
3.7 Offset Adjustment and Check for Absence of Feedback Effects.............................................39
3.8 Optimization of the Control Behavior .......................................................................................39
4. Service Information......................................................................................................................41
4.1 General Fault Tracing ..............................................................................................................41
4.2 Short Circuit in the Output Stage .............................................................................................42
4.3 Replacing the Control Electronics............................................................................................43
4.4 Replacing the Driver Electronics (with ballast circuit) ..............................................................44
4.5 Replacement Parts...................................................................................................................45

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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Table of Figures
Figure 1: Block Diagram, Transistor Servo Amplifier, Series 20K.......................................................... 9
Figure 2: Basic circuit diagram of the output stage .............................................................................. 11
Figure 3: Simplified basic circuit diagram............................................................................................. 12
Figure 4: Voltage waveforms in the output stage................................................................................. 13
Figure 5: maximum pulse current duration as a function of the recovery time an the current boost
factor............................................................................................................................................... 21
Figure 6: maximum pulse current duration as a function of bias and current boost factor .................. 21
Figure 7: Example of a working diagram.............................................................................................. 22
Figure 8: Standard commutation characteristics.................................................................................. 25
Figure 9: Proposed circuit for dynamic brake....................................................................................... 26
Figure 10: Fuse protection for multiple shaft operation with same nominal voltage ............................ 28
Figure 11: Power supply for unequal nominal voltages ....................................................................... 29
Figure 12: Fuse protection for mechanically coupled shafts ................................................................ 30
Figure 13: Connections diagram for series 20K units .......................................................................... 32
Figure 14: Connections diagram for series 5K units ............................................................................ 33
Figure 15: Components layout diagram for control electronics............................................................ 47
Figure 16: Circuit diagram of the preamplifier ...................................................................................... 48
Figure 17: Components layout diagram for driver electronics.............................................................. 49
Figure 18: Circuit diagram of ramp generator ...................................................................................... 50
Figure 19: Components layout diagram of ramp generator ................................................................. 50
Figure 20: Components layout diagram for electronics and ballast circuit........................................... 51
Figure 21: Components layout for driver module ................................................................................. 52
Figure 22: Dimensions of Series 20K unit ............................................................................................ 53
Figure 23: Dimensions of Series 5K..................................................................................................... 54

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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1. Technical Description
1.1 General Information
The Series 5K and 20K transistor servo amplifiers are pulse width modulated amplifiers which have
been conceived primarily for driving DC servo motors with permanent excitation. These devices oper-
ate in four-quadrant mode, i.e. the connected motor can drive or brake in both senses of rotation,
whereby a boosted pulse torque greater than the continuous torque is available for short periods. This
feature makes these servo amplifiers particularly suitable for driving machine tool feed spindles, but
other applications are possible too (especially for the series 20K units), e.g. antenna drives.
1.2 Special Features
A new kind of modulation technique is used, in which no audible modulation sounds are emitted from
the motor or from chokes, i.e. the objectionable whistle or howl emitted by many conventional chopper
amplifiers, is here completely absent. The iron losses in the motor and chokes (magnetic hysteresis
losses in the magnetization cycle) are smaller by an order of magnitude compared with those involved
in conventional modulation methods.
The series 20K devices incorporate electrical isolation between the open loop control input side and
the load side, so that a single-wound transformer may be used instead of a double-wound transformer
for power supply. The case is electrically insulated with respect to the device.
The series 5K devices feature self-cooling, i.e. a blower is not required for forced air cooling. These
units employ essentially open construction, i.e. with no special case to contain them.
Both series of units contain a three-phase bridge rectifier for power supply and a generously dimen-
sioned ballast circuit to dissipate the braking energy. Power supply is optional with three-phase alter-
nating current or with direct current. A 230V / 50Hz auxiliary supply is required only to power the blow-
er fan in series 20K units. The control electronic circuitry is powered directly from the principal supply
via incorporated voltage converters.
Supply voltage fluctuations within wide limits are tolerated in operation (60V – 150/200V; briefly 50V –
175/230V). This permits full battery operation for the series 5K units, and an “emergency run” operat-
ing mode for the series 20K units, for example to steer to a safe position in battery operation without
blower fan on mains voltage failure. Both types of unit contain storage chokes permitting direct con-
nect-up to any motor or other kinds of load. Self-heating is very small, by virtue of the high power effi-
ciency (95 – 96% at 200V nominal voltage). Thus the required cooling facilities for the equipment cab-
inet remain within reasonable limits even when several drive shafts are incorporated.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 6
The units incorporate protection circuits for current overload, overvoltage, undervoltage and overheat-
ing, as well as an optional plug-in commutation current limiter (IAmax = f(UA)) and standard feature I2t
current limitation. Furthermore, inputs are provided for direction-dependent limit switches, output stag-
es enable and cut-out of the integral control function. Response of the I2t current limiter is signaled via
an open collector output. When the unit is functional, a floating relay contact closes.
1.3 Summary of Types
Unit Designation Nominal Voltage
(V)
Nominal Current
(A)
Pulse Current
(Ampere, max.3s)
Series
MTR 150 / 10-B 60 – 100 10 18
5K
MTR 150 / 25-B 60 – 150 25 40
MTR 150 / 35-B 60 – 150 35 60
MTR 200 / 10-B 60 – 200 10 18
MTR 200 / 25-B 60 – 200 25 40
MTR 200 / 35-B 60 – 200 35 60
MTR 150 / 50-B 60 – 150 50 100
20K
MTR 150 / 70-B 60 – 150 70 150
MTR 150 / 100-B 60 – 150 100 200
MTR 200 / 50-B 60 – 200 50 100
MTR 200 / 70-B 60 – 200 70 150
MTR 200 / 100-B 60 – 200 100 200

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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1.4 Technical Data
Voltage range of control inputs ±10V
Internal impedance of the control inputs 20kOhms
Setting range of the input attenuator 0.18 … 1.1
Maximum tachovoltage for Ui= ±10V ±100V
Internal impedance of the tacho-input (min.) 11kOhms
Setting range of the tacho-attenuator 0.065 … 0.65
Maximum input drift ±15µV / °C
Output current form factor for nominal current max. 1.01
Bandwidth of subordinate current controller 1kHz
Clock frequency of output stage 8.5kHz
Isolation voltage between preamplifier and output stage ±1500V DC
Pulse currents of ballast circuit (5K / 20K) 40A / 120A
Continuous duty power dissipation of the ballast circuit (5K / 20K) 275W / 4.4kW
Contact rating of signaling relay 100V / 0.1A / 10W
Power supply outputs for external auxiliary circuits ±15V / 20mA
Action mode of inputs for limit switches and
output stage enable:
-10 / 11 / 16 -
Normal run only when contact closed.
The function of the particular input is true when the
contact is opened (e.g. pos. Stop).
Reference potential M2.
Armature current monitor output:
- 19 -
±10V corresponding to the device pulse current, Ri
= 1kOhm.
Reference potential M1.
I²t signaling:
- 20 -
For active current limiting, sinking to 0V; otherwise
open circuit voltage +15V.
Reference potential M1.
Control output for dynamic brake: Open collector, sinking to 0V only when unit is
operational and the output stage is active.
Message output for “ready for operation”:
- 23 / 24 -
Reed contact, closed when unit is ready for opera-
tion, also when output stage is switched clear.
Storage temperature: -10°C … +60°C
Ambient temperature for nominal operation: 0°C … +45°C
Ambient temperature with max. 80% load: 0°C … +55°C
Mounting instructions (only 5K): Wall mounting, cooling fins vertical, ballast resistor
at top
Tolerated further run time at nominal current
without fan (only 20K):
2 minutes starting in normal operating temperature
state
Power dissipation at nominal current: 10A: 80W
20A: 250W
35A: 280W
50A: 500W
70A: 700W
100A: 1100W
Mechanical attachment: With 4 screws on flat surface
Dimensions (length x width x height): Series 5K : 210 x 260 x 216 mm
Series 20K : 440 x 218 x 255 mm
Weight: Series 5K : 3.5kp
Series 20K : 18kp

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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Transistor Servo Amplifier, Series 20K, Block Diagramm
1) Input 1
2) Input 2
3) Tacho-input
4) Difference amplifier
5) Difference amplifier
6) Tach-matching
7) Pulse current
8) Nominal current value
9) CW – limit switch
10) CCW – limit switch
11) Output ±15V / 20mA
12) Integral off (inv.)
13) Output stage enable (inv.)
14) Armature current monitor
15) I²t signaling
16) Relay for brake
17) Message contact for “ready” (closed
when ready)
18) Enable delay 30msec
19) External enable
20) Limit switches logic
21) Soldered jumper connection B1
22) Open an closed loop control elec-
tronics
23) Plug-in location for special circuit
24) Offset
25) Speed control amplifier with limiter
26) Electrical isolation ±1500V DC
27) Drift (for limit switches) and switch-
on jerk suppression circuit
28) Negative feedback network
29) Gain
30) Analog buffer amplifier and power
supply for preamplifier
31) Speed controller enable
32) Output stage enable
33) Optocoupler
34) Optocoupler
35) Protection circuits for current over-
load, overvoltage, undervoltage,
overtemperature, blocking (control
enable function)
36) General enable
37) Ready for operation
38) Current controller and driver enable
39) 8kHz clock generator, pulse width
modulator and delay circuit
40) Nominal current value limiter
41) PI-type current regulator
42) Armature current measuring circuit
43) Plug-in module for speed-dependent
current limiting
44) I²t measuring circuit
45) Armature voltage measuring circuit
46) Armature current actual value
47) I²t signaling
48) DC/DC voltage converter 60 – 200V
to ±15V
49) Driver electronics
50) Output stage driver circuit
51) Four-quadrant output stage
52) Safety chokes output
53) Blower, 230V
54) IAsensing lines
55) UAsensing lines
56) Control electronics for ballast circuit
57) Ballast resistor
58) Reservoir electrolytic capacitor
59) 3-phase power supply
60) 3-phase bridge rectifier, 100A

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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Figure 1: Block Diagram, Transistor Servo Amplifier, Series 20K

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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1.5 Functional Principles and Basic Circuit Dia-
grams
The following explanations are chiefly confined to the special features and technical innovations of
these units. In this section it is assumed that the reader is familiar with the general principles and pos-
sible applications of servo amplifiers. The basic circuit diagrams, respectively for the series 5K and
20K units, form the basis for the description.
1.5.1 Free Nominal Voltage Choice
The standard version servo amplifiers (150Volts) may be operated with any nominal supply voltage in
the range from 60 to 150Volts. The series with extended power supply voltage range (200V) permits
nominal supply voltages from 60 to 200Volts. The particular chosen nominal supply voltage is deter-
mined by the secondary voltage of the mains transformer. It is important to ensure that rectified volt-
age can not drop below 50V even when full pulse current is being drawn, and that the worst case open
circuit voltage is never greater then 175V (or 230V for 200V). The corresponding rms voltages for the
highest allowed values are 125V rms and 163V rms respectively in idle state. The ballast circuit may
become damaged if these limits are not observed.
Depending on the particular application, the mains transformer rating is usually much smaller than the
product of nominal current and nominal voltage, especially when speeds are required only rarely.
This is permissible because the output stage draws only the power level from the transformer which it
actually passes-on to the motor. This power is not only a function of the output current, but also of the
output voltage. The output stage of the unit performs a kind of impedance transformation, i.e. at slow
motor speed it transforms the relatively large intermediate circuit voltage at low current drain to the low
armature voltage at high armature current. Thus, for example, in the extreme case of “short circuit
across the motor terminals”, even 100Amperes output current causes only about 4.5A rms current to
flow the transformer to the rectifier circuit.
The possible saving is 50% without any problems, in the case of a single-shaft system and predomi-
nantly dynamic load. In a multiple shaft system, the saving may be much greater still, depending on
the load distribution in time. Therefore it may be useful to measure the actually required transformer
power in system operation.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 11
1.5.2 Auxiliary Voltage
Both series of units (5K / 20K) contain an auxiliary power supply for the control electronics and driver
circuit. This power supply circuit is connected in parallel to the DC intermediate circuit and automati-
cally matches itself to the voltage specified in Section 1.5.1. For the series 5K units, this obviates the
need for an external auxiliary power supply voltage.
However, the series 20K units contain a blower fan which must run on 230V AC supply. When the
system is connected to a mains circuit without neutral line conductor, the blower fan can be connected
either to its own auxiliary winding on the principal mains transformer, or it may be connected in parallel
with one of the three primary windings (only for mains voltage 3 x 400V, transformer primary operated
in star circuit).
For emergency operation on a battery, the series 20K units may be operated a short time without the
blower fan (max 2minutes at 100A nominal current). A considerably longer running time without forced
air cooling with considerably reduced load is permissible only when the inductive component of the
load is not smaller than 0.3mH. On account of the danger of overheating inside the unit, operation
without blower fan must be confined to short periods in real emergency situations.
1.5.3 Function Principles of the Output Stage
Figure 2: Basic circuit diagram of the output stage
The output stage of the units essentially consists of the 4 sets of transistors T1 – T4, each with a par-
allel-connected inverse current diode D1 – D4, and the intermediate circuit capacitor C as well as the
storage chokes Dr1 and Dr2.
For the following explanation of the circuit action, it is assumed for simplification that each half of the
output stage behaves like an ideal switch (without commutation break or overlap)(see Figure 3).

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 12
Figure 3: Simplified basic circuit diagram
This way of looking at the circuit is correct, because in actual operation, one transistor and one diode
at a time (e.g. T1 with D2 and T4 with D3) function like such a changeover switch. Depending on the
power and current direction, the rest of the output stage thereby is “blind”, so that the actual switch-
over pauses between the transistor conduction phases are not evident.
The output stage operates with impressed voltage, i.e. the motor is connected at all times to a certain
direct voltage source with low internal impedance. The inductance of the storage chokes is dimen-
sioned such that, on the one hand, the harmonics content (undulation, form factor) of the output cur-
rent is small in spite of the rectangular voltage waveform and, on the other hand, the inductance is still
small enough to ensure negligible disturbance of the motor behavior. Therefore only the arithmetic
mean value of the difference voltage U1 – U2 = UA(averaged over one clock cycle) is of importance
for the motor.
Figure 4 shows typical voltage waveforms for three different output voltages. Of particular importance
here is the fact that the voltage/time waveform of the output voltage UAshows a frequency-doubling
effect with respect to the voltage waveform at each one of the two output lines U1 and U2. This means
that the current undulation has a fundamental frequency of 17kHz in spite of the relatively low clock
frequency of 8.5kHz. Sine 17kHz lies above the audible limit for human ears, the modulation whistle of
former circuit concepts is absent here.
Nevertheless, these servo amplifiers do not fall into the category of radio frequency devices, which
would be subject to approval for operation when the operating frequency lies above 10kHz. When
these amplifiers are properly connected-up and operated as specified, the total generated radio inter-
ference level is only the sum of the individual interference levels on the output lines with respect to
ground, and the fundamental frequency in this sum is only single clock frequency of 8.5kHz (see U1(t)
+ U2(t) in Figure 4).

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
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Figure 4: Voltage waveforms in the output stage

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 14
Further important features here, compared with conventional modulation procedures (with simple di-
agonal commutation) are the facts that no AC loading at all is present when the motor is at rest, and
even in the worst case (when UA= ½ Ucc), the alternating voltage across the load is not equal to the
doubled, but only the single supply voltage. This almost eliminates motor heat-up by magnetic hyste-
resis losses (for motors with armature containing iron), whereas this consideration was formerly a
serious load limiting factor. This also makes it possible to use storage chokes of so small physical size
that they can still be accommodated inside the amplifier case even for 20kW nominal power rating.
1.5.4 Electrical Isolation
The series 20K units contain an analog buffer (isolating) amplifier which electrically isolates all major
control inputs from the remainder of the unit. This makes possible the use of a low-cost single-wound
mains transformer for the power supply. The entire power section is then tied to mains potential (or to
–Ucc / 2 measured with respect to ground), whereas the entire preamplifier circuit can be tied to any
other desired potential (usually signal ground potential of the numerical control system). The stray
coupling capacitance between the preamplifier and the basic unit is only a few picofarads. The analog
data (nominal armature current value) is transmitted magnetically and the digital commands (output
stage enable, speed controller enable) are transmitted via optocouplers.
The heat sinks of the output stage, the cores of the storage chokes and the cans of the intermediate
circuit electrolytic capacitors are mounted electrically insulated with respect to the case. To fulfill safety
requirements, the amplifier and motor case must be grounded. Failure to comply with this requirement
can lead to a dangerous situation (electric shock hazard).
It is also important to ensure that the preamplifier is not operated with floating potential. Apart from the
danger of damage to the optocouplers by static charge build-up in the floating state, in most cases
stray RF currents on the input lines would interface with proper operation of the output stage, manifest
as unstable zero point, jerky running, “scratching” noises and other effects. Therefore the entire input
circuitry must be tied to some well defined potential which is grounded with respect to RF signal volt-
ages. Terminal 17 can be used for this purpose.
If electrical isolation is not required, a jumper connection must be placed between terminals 17 and
18.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 15
1.5.5 Limit Switch Input with Automatic Braking
When a limit switch is reached, i.e. when the corresponding limit switch circuit is broken, a braking
process is initiated immediately, whereby the motor is braked down to rest with the maximum possible
current defined by the current limiters. This is effected by switching off the nominal speed value
(speed set point) to zero. The motor is thereby braked on an essentially linear characteristic, so that it
comes to rest much sooner than with a resistor brake which operates on an exponential characteristic
to a first approximation.
When a limit switch is in the actuated state, the amplifier responds only to nominal values (set point
commands) for the opposite direction of movement, i.e. the motor can be driven away from the limit
switch again without any problems. To prevent drift, the integral control function of the speed controller
is suppressed as long as a limit switch is in the actuated state.
In contrast to the function “output stage switch clear” (kl.16), the output stage remains in the operating
state when one or both limit switches are in the actuated state. Thus switching operations in the arma-
ture circuit are not permitted at such times under any circumstances.
1.5.6 Blocking Protection
Many servo motors will tolerate full rated operating current only for short times when at rest. For ex-
ample, if the motor comes inadvertently against a mechanical stop or brake, it may suffer damage
even though the I²t current limiter responds after some time. Therefore the units incorporate a monitor
which is triggered by response of the I²t current limiter and switches the output stage clear with current
overload status signal output if the I²t current limited status persists for 30seconds in one uninterrupted
stretch.
1.6 Overview of Terminals
Nominal Value Input 1 (Kl. 1-2):
These are the input terminals of the first difference amplifier. The maximum permissible voltage is
±10Volts, whereby neither one of the two terminals may ever carry a higher voltage than +20Volts or a
lower voltage than –20Volts with respect to terminal 17 (preamplifier ground), since otherwise the am-
plifier would be overdriven. Terminal Kl.1 functions positive with respect to terminal Kl.2.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 16
Nominal Value Input 2 (Kl. 3-4):
These terminals have the same function as for the terminal value input 1. The two inputs act on the
servo amplifier in superimposed manner without mutual back-interaction. When the potentiometers
P1, P2 are turned up to maximum, the sum of both nominal values must not exceed 10V. Terminal
Kl.3 functions positive with respect to terminal Kl.4.
Tacho-Input (Kl. 5-6):
These terminals are provided for connecting a direct voltage tachogenerator as motor speed transmit-
ter. The tacho-voltage at nominal motor speed an with 10V control voltage, should be at least 17Volts
and must not exceed 100Volts. The negative pole must be connected to terminal Kl.5.
Speed Controller Output and Nominal Current Value Input (Kl. 7 and 8):
In normal operating mode, these two terminals must be connected together. If pure current control is
not desired, the jumper connection must be removed and the nominal current value signal (±10V for
full pulse current, with respect to terminal Kl.17) must be injected at terminal Kl.8. The current limiter
circuit are operative in this circuit mode too.
Limit Switch “Positive Stop” (Kl. 9-10):
For normal operation, these terminals must be connected together by the limit switch contact. When
this connection is broken or when +15V is applied to terminal Kl.10, the amplifier no longer responds
to positive nominal speed value signals (for definition of polarity, see “nominal value input”). The actual
input terminal is Kl.10; the terminal Kl.9 lies at amplifier ground potential (like terminal Kl.17).
Limit Switch “Negative Stop” (Kl. 11-12):
Same function as for “positive stop”, but for negative nominal values. The input terminal is Kl.11; ter-
minal Kl.12 lies amplifier ground potential.
Auxiliary Voltages +/-15V (Kl. 13-14) :
External auxiliary circuit or nominal value transmitters can be connected here. If used for nominal
value definition, the voltage must be stabilized additionally in the external circuit, e.g. to 10Volts with a
Zener diode and series resistor. The maximum permissible current loading is 20mA for each terminal.
Terminal Kl.13 is for +15Volts and terminal Kl.14 is for –15Volts, in each case witch a tolerance of
±5%.
Control Input “Integral Control Function Off” (Kl. 15):
Particularly in a system with higher priority position controller, the integral characteristic control func-
tion is not desired in all phases of a positioning process. It could lead to overshoot especially when
homing to the zero position after a fast run process. To suppress such unwanted effects, the integral
characteristic control function of the motor speed controller can be inactivated via this input for the
duration of the shaft control process in which it is not required. The integral function is enabled when
this input is open. When 0V applied (short circuit connection to terminal Kl.17), the integrating capaci-
tor is shorted by a field effect transistor.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 17
Output Stage Switch-Clear (Kl. 16-17):
The servo amplifier operates only when the terminals Kl.16-17 are shorted together. When this con-
nection is broken or when +15V potential is connected to terminal Kl.16 with respect to terminal Kl.17,
the current is switched off in the output stage after not longer than 1mseconds. At the same time a
switch transistor cuts-off at terminal Kl.22; this can be used, for example, to control a braking circuit
(see control output for dynamic braking”). When the connection between terminals Kl. 16-17 is broken
or when 0V is connected to terminal Kl.16, the aforementioned switch transistor conducts immediately
and after elapse of not longer then 30mseconds, the output stage is enabled.
All integral characteristic control functions are disabled for the duration of actuation (open circuit in-
put), so that a switch-on jerk is prevented.
Preamplifier Zero Potential (Kl. 17):
The preamplifier circuitry must be tied to a definite zero potential in all operating modes, preferably to
ground potential or to the potential of the output stage. This can be established via the terminal Kl.17.
Output Stage Common (Kl. 18):
This is the terminal for the jumper connection to terminal Kl.17 when operating the system with a dou-
ble-wound mains transformer. It is also the reference zero potential for the armature current monitor,
for the I²t status signal and for the second auxiliary voltage +15Volts (terminal Kl.12) for the braking
relay.
Armature Current Monitor (Kl. 19):
The armature current actual value signal is connected to this terminal (±10Volts correspond to the
respective data sheet pulse current rating with a tolerance of about ±3%). The terminal impedance is
about 1kOhm; a short circuit at this terminal or long unshielded line connected to it may lead to im-
proper functioning.
I²t Status Signal (Kl. 20):
In the normal operating state, this output is pulled down to 0V. A few milliseconds after response of
the I²t current limiter, this output goes to high impedance state. This status signal can be used to in-
form a higher priority controller, whether or not the servo amplifier is overloaded.
Control Output for Dynamic Brake (Kl. 21-22):
The control relay for a dynamic brake (resistor brake) can be connected here. Actuation is by the al-
ready described input for the output stage enable/disable. In the normal operating state of the unit, a
transistor conducts to pull terminal Kl.22 down to 0V. +15Volts potential is terminal Kl.21. The current
loading and sinking capability is 20mA.
Status Signal Contact for “Ready to Operate” (Kl. 23-24):
A floating reed contact is connected to these terminals. It is closed only when the unit is ready for op-
eration. The enable input (terminal Kl.16) has no effect on the state of this contact. The maximum
contact ratings are: 100V / 0.1A or 10Watts.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 18
Auxiliary Power Supply 230V AC (Kl. 31-32, only for series 20K):
Nothing is connected here apart from the blower fan, so that the unit may be operated in an emergen-
cy for a short time without this auxiliary power supply, by virtue of its thermal inertia. However, proper
temperature supervision of the unit is not possible in such operating mode, so that operation without
blower fan must never be prolonged until the thermal cut-out operates. The power consumption of the
blower fan is about 40VA.
Main Power Supply 3 x 50V to 3 x 115/145V (Kl. 33-34-35):
Normally the power supply input for the entire amplifier is taken via these terminals. An essential con-
dition is that medium delay fuse cartridges with about ⅔to ¾ of the nominal full current rating for the
unit, must be interposed in the input circuit. These fuses do not protect the amplifier in the case of
overload, but they minimize consequential damage in the case of output stage failure.
Direct Current Intermediate Circuit (Kl. 36-37):
Direct access to the power supply for the output stage is provided via these terminals. As an alterna-
tive to an AC mains supply, the units can be powered directly with a DC supply via these terminals, or
several units can be connected in parallel here to a common supply. If the motor has field excitation
winding, it may be connected here too. Terminal Kl.36 is positive with respect to terminal Kl.37.
Motor Connections (Kl.38-39):
All kinds of servo motors with suitable nominal current rating can be connected here. Since the servo
amplifier units already contain storage chokes, it is not necessary to comply with any minimum induct-
ance specification for the servo motor (with one exception: Lmin = 0.3mH for operation of series 20K
units for any appreciable time without blower fan).
Ballast Resistor (Kl.40-41, only for Series 20K):
On account of the large heat dissipation of up to several kilowatts, the ballast resistor for series 20K
units is not incorporated inside the amplifier case. Depending on actual power dissipation, any high-
power resistor with a value of 1.8 or 2.2Ohms may be connected to these terminals. Terminal Kl.40 is
the actual output of the ballast output stage whereas terminal Kl.41 is always connected to 0V (for
resistance value calculation, see Section 2.6).

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 19
2. Projecting and Dimensioning
2.1 Load Category
Two categories of applications may be distinguished: feed drive and main drive. A typical feed drive,
such as may be attached to the spindle of an xy-coordinates table, is characterized primarily by rela-
tively short acceleration times (some tens to hundreds of milliseconds) and by the predominance of a
dynamic load component over the static load component. Current is required primarily for acceleration
and for braking, and only to a smaller extent for overcoming friction or other continuous load.
In contrast hereto, a typical main drive is required to cope with very large moments of inertia, which
come in part from the driven load but which may also originate from the motor itself. Therefore cus-
tomary acceleration times have the order of magnitude of seconds. Furthermore, the static load com-
ponents (friction, wind load, wire tension, etc.) usually represent a considerable friction of the total
required torque.
As far as the servo amplifier is concerned, a feed drive constitutes the less critical application case, by
a long way, and this remains true in general even when very high clock frequencies are demanded
with full exploitation of pulse current and rms current capability. The reason is the only slight thermal
alternation loading of the output stage transistors by brief current pulses.
In the case of main drives, however, with full pulse current the transistors are heated to the thermal
limit and cooled down again on each load cycle. Although this thermal stress does not give rise to any
imminent danger of failure (each unit is tested on continuous duty in the extreme case of this kind
loading, before delivery, the failure safety margin is nevertheless reduced, particularly in continuous
operation. Reduction of the allowed pulse current to about 150% of I nominal is therefore recommend-
ed. The further prolongation of the run-up times entailed thereby are no longer critical for the amplifier.
This reduction is made automatically by the I²t current limiter after a few seconds (cf. diagrams in Fig-
ure 5 and 6), but at this time transistor chips are already hot. Therefore it is advisable as a matter of
course for main drives, to reduce the pulse current at the potentiometer control provided for this pur-
pose (P6) or with a fixed resistor (R144). In most cases response of the I²t current limiter can be
avoided thereby, and this also avoids the accompanying change of acceleration.

TECHNICAL DESCRIPTION „MTR 5K, MTR 20K“ Edition 1.00
Page 20
2.2 Optimizing the Drive for Given Amplifier Pow-
er
If it is possible at the time of planning the drive, to provide matching by gears or other form of speed
transformation (cog chain, spindle, etc.), then this speed reduction should always be chosen such that
load moment of inertia as reflected into the motor shaft is equal to the input moment of inertia of the
motor. This gives the shortest possible load run-up time with a given accelerating current. An excep-
tion to this rule is found only if the speed transformation ratio required for this matching would exceed
the maximum possible motor speed. In this case the speed transformation must be based on the max-
imum available motor speed.
Another kind of matching is possible for some motors by choosing the appropriate nominal motor
speed. Such motors usually have various windings, and the relationship between speed and torque
factor is approximately one of inverse proportion. Since the moments of inertia are the same, in most
cases the better choice is the slower running motor.
2.3 Determination of the RMS Current for Dynam-
ic Load
When the motor type and speed reduction transmission have been chosen and the overall moment of
inertia has been calculated, the armature current as a function of time can be determined in relation to
the given pulse current and torque factor. Neglecting friction, the run-up time is given by:
60
*2
**
*
π
n
KI totalJ
t
Mb
b=
where: tb= Run-up time in seconds
J total = Sum of motor and load moments of inertia in kgm²
I
b= Acceleration output current provided by the amplifier
K
M= Torque factor of the motor in Nm/A
N = Speed change in rpm
The same formula also holds for braking. According to the particular application, a working diagram
like Figure 7, for example, may be obtained.
Therewith the probable rms current can be determined according to the following equation, provided
that the complete cycle is actually taken into account:
tntt tItItI
Inn
rms +++
+++
=K
K
21
2211 *²*²*²