Gossen MetraWatt SSP 120 Series, Operating Instructions Manual

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54 GMC-I Messtechnik GmbH
5.9.2 Master-Slave Parallel Connection
Functions
As opposed to direct parallel connection, master-slave parallel
connection offers significant
advantages :

Equally suitable for voltage and current regulation

Output parameters (output voltage, cumulative current limiting,
output on/off) are set entirely by the master device .

All interconnected KONSTANTERs are equally loaded .
Connection

Define one power supply as a master device .

Connect master and slave devices as shown in Figure 5.9.2.

Connect the output leads ( refer to chapter 2.1.5).

Balance the individual output current values . Keep connector
cable as short as possible, and use the largest possible
conductor cross-section. Perform balancing with R R
sym
.
Figure 5.9.2 Wiring for Master-Slave Parallel Connection
Settings
Initial power-up:

Short circuit the load.

Switch the master on (mains) and configure settings:
SIG1 out
Pon rcl
OUTPUT off
USET = Uset Desired output voltage
ISET = Isoll / n Iset: Desired cumulative current
n: Number of devices
Only valid if nominal data are
identical for all devices, see notes.

Switch slave 1 on (mains) and configure :
trG out
SIG1 out
Pon rcl
USET > USET
master
The voltage setpoint at the slave devices
must be set at least 1% higher than at the
master device, e.g. to maximum.
ISET = 0 A The ISET rotary knob can be deactivated if
desired by setting ILIM to 0 A.

Use the same procedure for additional slave devices.

Press the OUTPUT ON key at the master. All slave outputs are
switched on simultaneously and configured.

Check output current at the slave device displays.

Output current at each of the slaves can be precisely matched to
master output current by adjusting R
sym
. Changes appear
immediately at the respective display.

Undo short-circuiting of the load.

From this point on, setting and regulation of (cumulative) output
parameters are controlled entirely by the master device.
Power-up after initial settings:

Devices can be switched on and off in any desired order .
Functional Principle

The master controls output current of the downstream device
(slave 1) via the slave’s
current control input with the help of the
current monitoring signal .

Slave 1 functions as a master device for the next downstream
slave ( slave 2 ), and so forth.
Cumulative output current is thus always proportional to
master output current.
The master controls the output on / off status of the slave
devices via the connection from the master SIG1 output ( SIG1 out
setting ) to the Slave TRG input ( trG out setting ).
Notes:
KONSTANTERs with Differing Nominal Values

The KONSTANTER with the smallest nominal voltage value must
always be used as the master device.

The voltage setting range of the other KONSTANTERs must be
limited to this lowest value with the ULIM parameter.

Slave output current Iout corresponds to master output current
Iout as a percentage only, relative to I
nom
.
Example:
General

A wire connection can be used instead of R
sym
if no precise
setpoint value is required for cumulative output current. In this
case, each slave device supplies slightly more current than the
master device.

If analog interface connector cables and the sensing leads are
longer than 1 meter , shielded cable should be used.
The shield is connected to the ground terminal on the housing or
to

OUT .

The master device’s measuring function acquires commonly
generated output voltage for all interconnected KONSTANTERs,
but only acquires its own output current .
The individual measured current values for each of the
interconnected KONSTANTERs must be
added together in
order to arrive at cumulative output current .
+ SENSE

OUT

OUT

SENSE
Analog Interface
SIG1 OUT
SIG2 OUT
TRG IN

TRG IN

+15 V
AGND
Uset

Uset +
Iset +
U-MON
I-MON
+ OUT
+ OUT
Master
Settings
USET = Uset
ISET = Iset / n
OUTPUT on/off
+ SENSE

OUT

OUT

SENSE
Analog Interface
SIG1 OUT
SIG2 OUT
TRG IN

TRG IN

+15 V
AGND
Uset

Uset +
Iset +
U-MON
I-MON
+ OUT
+ OUT
Slave 1
Settings
USET > Uset
master
ISET = 0 A
OUTPUT on
+ SENSE

OUT

OUT

SENSE
Analog Interface
SIG1 OUT
SIG2 OUT
TRG IN

TRG IN

+15 V
AGND
Uset

Uset +
Iset +
U-MON
I-MON
+ OUT
+ OUT
Load
= only required for sensing mode operation
1 k

Slave 2
Settings
USET > Uset
master
ISET = 0 A
OUTPUT on
1 k

Output
Output
Output
R
sym
R
sym
trG out
SIG1 out
trG out
SIG1 out
SSP KONSTANTER
SSP KONSTANTER
SSP KONSTANTER
Master : SSP 120-20 U
nom
20 V I
nom
10 A
Settings: USET : 12 V ISET : 3 A (30%)
Slave 1 : SSP 120-20 U
nom
20 V I
nom
10 A
Results in Uout : 12 V Iout : 3 A (30%)
Slave 2 : SSP 120-40 U
nom
40 V I
nom
6 A
Results in Uout : 12 V Iout : 1.8 A (30%)