Elmo SSA Series Installation instructions

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SSA - Rev 6/98
Rev 6/98

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SSA - SAFETY INSTRUCTIONS
Read this page carefully before installation and use of the instrument, and
follow all instructions in section 6 of Installation Procedures for safe
installation of this product.
INTRODUCTION
The following clauses contain information, cautions and warnings which must be
followed to ensure safe operation and to retain the instrument in a safe
condition.
As this product is intended for incorporation into a machine or end-product,
the end product must comply with all safety aspects of the relevant requirements
of the European Safety of Machinery Directive 89/392/EEC as amended, and with
those of the most recent versions of standards EN60204-1 and EN292-2 at least.
Installation, adjustment, maintenance and repair of the instrument shall be
carried out only by qualified personnel.
WARNINGS
Any removal from the structure or removal of parts, except those to which
access is permitted, is likely to expose live parts and accessible terminals
which can be dangerous to live. If afterwards any adjustment, maintenance or
repair of the opened instrument under voltage is inevitable, it shall be carried
out only by a qualified person who is aware of the hazard involved.
The instrument shall be disconnected from all voltage sources before it is
opened (for service method).
Any interruption of the protective earth conductors inside the instrument, is
likely to make the instrument dangerous.
Components which are important for the safety of the instrument, may only be
renewed by components obtained through Elmo service organization.
Before switching on, ensure that the instrument has been installed in
accordance with the Installation Instructions.
Maximum DC supply according the types described in the operating manual.

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SSA - Rev 6/98
How to use this manual - Flow Chart
The SSA amplifier is designed for OEM applications. It enables the user to
adjust the amplifier for various types of motors and to save valuable adjusting
time in repetitive applications.
Use the following flow chart in order to determine the chapters that you should
read. If you are a new user of the SSA, you should read chapters 1-4 which will
familiarize you with the product.
Read chapter 5.1
Read chapter 6 - Installation
Read chapter 7.1 - Start-Up
Read chapters
1,2,3,4
Familiar with the SSA ? no
no
Read
7.3
Brush Tacho ?
Read
7.2
Read chapter 8 - Adjustments
Read chapter 9 - Summaries
no
Using SIB-SSA interface ?
Terminals
Read chapters 5.1+5.2 Terminals
Armature voltage feedback ? no
(Current mode)

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TABLE OF CONTENTS
1. DESCRIPTION..........................................................................................................................7
2. TYPE DESIGNATION...............................................................................................................8
3. TECHNICAL SPECIFICATIONS...............................................................................................8
4. OPERATION OF THE SERVO CONTROL.............................................................................10
4.1 Inputs ..............................................................................................................................................................................10
4.2 Velocity mode..................................................................................................................................................................11
4.2.1 Velocity control using armature voltage feedback.......................................................................................................12
4.3 Current mode..................................................................................................................................................................12
4.4 Current loop....................................................................................................................................................................12
4.5 Current limits .................................................................................................................................................................12
4.5.1 Time dependent peak current limit.............................................................................................................................13
4.6 Protective functions.........................................................................................................................................................14
4.6.1 Short circuit protection ..............................................................................................................................................14
4.6.2 Under/Over voltage protection ...................................................................................................................................14
4.6.3 Temperature protection..............................................................................................................................................14
5. TERMINAL DESCRIPTION ....................................................................................................17
5.1 Terminals of the basic SSA.............................................................................................................................................17
5.2 Terminals for SIB-SSA...................................................................................................................................................19
6. INSTALLATION PROCEDURES............................................................................................20
6.1 Mounting.........................................................................................................................................................................20
6.2 Wiring.............................................................................................................................................................................20

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6.3 Load inductance..............................................................................................................................................................21
6.4 DC power supply ............................................................................................................................................................21
6.5 Wiring diagrams.............................................................................................................................................................23
7. START - UP PROCEDURES ..................................................................................................28
7.1 Common procedures for all amplifiers types.................................................................................................................28
7.1.1 Inhibit logic...............................................................................................................................................................28
7.1.2 Velocity mode............................................................................................................................................................30
7.1.3 Current mode.............................................................................................................................................................30
7.1.4 Static current limits ...................................................................................................................................................31
7.2 Velocity control using tachogenerator feedback............................................................................................................32
7.3 Velocity control using armature voltage feedback.........................................................................................................32
8. AMPLIFIER ADJUSTMENT AND DIAGNOSTICS..................................................................34
8.1 Balance adjustment ........................................................................................................................................................34
8.2 Verifying the static current limits..................................................................................................................................34
8.3 External Current Limit (ECL) adjustment....................................................................................................................35
8.4 Adjustment of the IxR compensation.............................................................................................................................35
8.5 Response adjustment (Velocity mode only)....................................................................................................................36
9. TABLES AND SUMMARIES ...................................................................................................38
9.1 Adjusting trimmers.........................................................................................................................................................38
9.2 LED diagnostics..............................................................................................................................................................38
APPENDIX A - RESPONSE ADJUSTMENT - CURRENT LOOP................................................39
SERVICE CENTERS AND WARRANTY......................................................................................44

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The SSA is a miniature PWM servo amplifier designed for DC servo motors. It
utilizes power MOSFETs which contribute to its high efficiency and compact
design. The SSA is constructed from two PCBs mounted on a heat sink plate. The
lower board contains the power switching transistors which drive the motor,
terminals for the power stage, the switch mode power supply and the protection
logic. The upper PCB contains the control logic, terminals for the control stage,
adjusting trimmers and indication LED's.
Standard features
* Four quadrant operation allows motor acceleration and deceleration under power
in both CW and CCW directions.
* Internal DC to DC converter allows for operation from a single supply.
* Zero deadband.
* Excellent linearity.
* 2 inputs.
* Motor current monitor.
* Inhibit/fault indication (open collector).
* Remote control functions: Inhibit and CW/CCW disable.
* Adjustable compensation.
* Continuous and peak current limits.
* Input balance (offset) adjustment.
* External current limit adjustment.
* Operation in two velocity modes (Tacho or armature voltage feedback) or current
mode.
* LED diagnostics.
* Removable terminals for easy installation and service.
The amplifiers are fully protected against the following faults:
* Under/over voltage.
* Shorts between: outputs, output to ground.
* Excess temperature.

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SIB-SSA
The SIB-SSA is an interface board for the SSA that is used to convert the SSA
flat ribbon connector to spring type Phoenix terminals. This board has the same
size as the SSA board and it can be assembled as an add-on card on top of any SSA
amplifier or as a separate panel mount unit.
The SIB-SSA is connected to the SBA amplifier via a 16 wires ribbon cable.
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SSA - 12 / 55 - 4
SSA amplifier
Rated current
Maximum rated voltage
Switching frequency
20KHz when not specified
4=40KHz, 6=60KHZ
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Type
DC Supply
Min-Max(V) *
*
*
Current limits
Cont/Peak(A)
Size
(mm)
Weight
Kg
SSA-12/55 10-55 12/30 100x65x30 0.2
SSA-6/100 20-100 6/15 100x65x30 0.2
SSA-8/100 20-100 8/20 100x65x30 0.2
SSA-5/200 40-195 5/10 100X65X30 0.2
* DC output voltage is 90% of DC input voltage.
* 20KHz, 40KHz or 60KHz switching frequency.
* 2KHz current loop response (minimum)
*
*
*These are the absolute minimum-maximum DC supply voltages under any condition.

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* Outputs voltages of +13V, (15mA each) for external use.
* Efficiency at rated current - 97%.
* Drift: 10µV/°C (referred to input)
* Operating temperature: 0-50°C.
* Storage temperature: -10 - +70°C.

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The SSA has 2 inputs: A single ended input (no.1) at terminal 1 and a
differential input (no.2) at terminals 3,4.
The current gain of input 1 (current mode) is given by:
66 x Ic
Gc = ----------- (Amp/Volt), R1 in Kohm
100 + R1
Ic - amplifier rated continuous current
The current gain of the differential input for R6=R7 (current mode) is given by:
6.66xIc
Gcd= --------- (Amp/Volt)
R7
R7 in Kohm
The current gain in velocity mode is given by (place the appropriate Gc for
each input):
50 x Gc
Gv = ---------- (Amp/Volt),
R11
R11 in Kohm
The maximum input voltage at terminal 1 is calculated by:
V1max= 8 + 0.08R1 (Volts), R1 in Kohm
The maximum input voltage at terminal 3,4 is calculated by:
Vdmax= 8 + 0.8R6 (Volts), R6=R7 in Kohm

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In this mode op amp U1/2 is employed as a high gain error amplifier. The
amplifier sums velocity command and the tachogenerator feedback signal, and
provides the necessary servo compensation and gain adjustments, resulting in
stable, optimum servo operation. This op amp is configured with two feedback
paths:
One, in the form of a resistive T network, controls the DC gain of this
amplifier. The equivalent value of a T network is given by:
1010
Rf = ------
R11
Resistor R11 (30 ohm) is mounted in solderless terminals so it can be changed
easily whenever the DC gain of the error amplifier is to be changed.
The second feedback path controls the AC gain by C3 (0.022 µF), R12 (475 Kohm)
and T1. Maximum AC gain is obtained with T1 set fully CW. Setting T1 fully CCW
removes AC gain and no lag in response occurs. R12 and C3 are mounted in
solderless terminals and can be easily replaced in cases when T1 range is not
enough to get optimum response (See 8.5 for details).
The output of the error amplifier is:
1 + SxC3xR12
Vo=(V1Gv1+V2Gv2)x[ ---------------------- ]
1 + SxC3xR12(1 + RfxK1/R12)
V1,V2, - Input signals
Gv1,Gv2- Gain of inputs.
K1 = Position factor of the wiper of T1.
Full CW = 1
Full CCW = 0.01