Gossen MetraWatt SSP 120 Series, Operating Instructions Manual

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56 GMC-I Messtechnik GmbH
5.10.2 Master-Slave Series Connection
Functions
As opposed to direct series connection, master-slave series
connection offers significant
advantages :

Equally suitable for voltage and current regulation

Output parameters (cumulative output voltage, 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 5.10.2.

Connect the output leads to the series circuit phase terminals .

Balance the individual output voltage values with R
sym
.

Balancing can be simplified and optimized by combining a fixed
resistor (metallic layer,
T
k

50 ppm / K) and a trimming resistor for R
sym
.
Figure 5.10.2 Wiring for Master-Slave Series Connection
Settings
Initial power-up:

Do not load the outputs (idle).

Switch the master on (mains) and configure settings:
SIG1 out
Pon rcl
OUTPUT off
USET = Uset / n Uset: Cumulative output voltage
n: Number of devices
Only valid if nominal data are identical for all
devices, see notes
ISET = Iset Current limit value

Switch slave 1 on and configure :
trG out
SIG1 out
Pon rcl
USET = 0 V The USET rotary knob can be deactivated if
desired by setting ULIM to 0 V.
ISET > ISET
master
The current setpoint at the slave devices must
be set at least 1% higher than at the master
device, e.g. to maximum.

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 voltage at the KONSTANTER displays.

Output voltage at each of the slaves can be precisely matched to master
output voltage by adjusting R
sym
. Changes appear immediately at the
respective display.

Connect 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 voltage of the downstream
KONSTANTER (slave 1) via the slave’s
voltage control input with
the help of the voltage monitoring signal .

Slave 1 functions as a master device for the next downstream
slave ( slave 2 ), and so forth.
Cumulative output voltage is thus always proportional to
master output voltage.
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 current value must
always be used as the master device.

The current setting range of the other KONSTANTER must be
limited to this lowest value with the ILIM parameter.

Slave output voltage Uout corresponds to master output
current Uout as a percentage only, relative to U
nom
.
Example:
General

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 same current value is available from all KONSTANTERs.
For this reason, current measured at the master device is sufficient
for the measurement of load current .
The individual measured voltage values for each of the
interconnected KONSTANTERs must be added together in
order to arrive at cumulative output voltage .
Slave,
Nominal Voltage
R
sym
,
Nominal Value
R
sym
,
Combination
20 V 40 k

/ 0.2 W 36 k

+ 10 k

pot
40 V 80 k

/ 0.2 W 75 k

+ 10 k

pot
80 V 160 k

/ 0.2 W 150 k

+20 k

pot
SSP KONSTANTER SSP KONSTANTER SSP KONSTANTER
+ 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 / n
ISET = Iset
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 2
Settings
USET = 0 V
ISET > Iset master
OUTPUT on
Load
R
sym
R
sym
+ 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 = 0 V
ISET > Iset master
OUTPUT on
Output
Output Output
= Only required for sensing mode operation
trG out
SIG1 out
trG out
SIG1 out
Master : SSP 120-40 U
nom
40 V I
nom
6 A
Settings: USET : 12 V (30%) ISET : 3 A
Slave 1 : SSP 120-20 U
nom
20 V I
nom
10 A
Results in Uout : 6 V (30%) Iout : 3 A
Slave 2 : SSP 120-40 U
nom
40 V I
nom
6 A
Results in Uout : 6 V (30%) Iout : 3 A