User manual

22 GMC-I Gossen-Metrawatt GmbH
5.8.2 Parallel Master-Slave Operation
Function
Parallel master-slave connection provides for significant advantages
as opposed to direct parallel connection:
• Equally suitable for voltage and current regulation
• Output parameters (output voltage, cumulative current limiting,
output ON/OFF) are fully controlled by the master.
• All interconnected KONSTANTERs are equally loaded.
Wiring
• Define one KONSTANTER as the master.
• Connect master and slave devices as shown in figure 5.8.2.
• Connect the power leads (observe instructions in chapter 2.2).
• Balance the individual current outputs. Keep the connector cables
as short as possible, and use the largest possible conductor
cross section. Perform balancing with R
match
.
Figure 5.8.2 Wiring for Parallel Master-Slave Operation
Procedure
Initial Start-Up:
• Short circuit the load.
• Switch the master on (mains switch) and set:
OUTPUT off
USET= Uset, desired output voltage
ISET= Iset / n, Iset: desired cumulative output current,
n: number of KONSTANTERs
Only valid if nominal values for all devices
are identical, see notes as well.
• Switch on slave 1 (mains switch) and set:
OUTPUT on The output remains inactive at first even though
the OUTPUT key is depressed, because it has
been disabled by the master via the TRG input.
USET > USET
master
The voltage setpoint value must be set at
least 2% higher at the slaves than at the
master, e.g. to maximum.
ISET = 0 A ISET rotary knob can be deactivated by
setting Ilim to 0 A.
• Proceed as described above for all slaves.
• Press the OUTPUT ON key at the master. All slave outputs are
switched on and set simultaneously in this way.
• Check the output levels displayed at the KONSTANTERs.
• Output current for each individual slave can be precisely set to
match output current at the master by adjusting R
match
. Changes
appear immediately at the respective display.
• Eliminate short-circuiting of the load.
• From now on, (cumulative) output parameters are set and
regulated entirely by the master.
Repeat Start-Ups (after initial start-up):
• The order in which devices are switched off and back on again
is irrelevant.
Functional Principle
• The master controls output current at the downstream device
(slave 1) via its current control input with the current monitor signal.
• Slave 1 functions as a master for slave 2 and so forth.
Cumulative output current is thus always proportional to output
current from the master.
The master controls the OUTPUT ON/OFF status of the slaves via
connection of the master SIG1 output to the slave TRG input.
Notes
Devices with Different Nominal Values
• The device with the lowest nominal voltage must be used as the
master.
• The voltage setting range for all other devices must be limited to
the lowest nominal value with the ULIM parameter.
• Iout
Slave
is only equivalent to Iout
Master
as a percentage
with reference to I
nom
.
Example:
General
• A wire conductor can be used instead of R
match
, if an exact setpoint
value is not required for cumulative output current. In this case,
each of the slaves always supplies somewhat more current than
the master.
• If the connector leads to the analog interface and the sensing
leads are longer than 1 m, use shielded cable.
Connect the shield to ground / housing or AGND.
• The measuring function at the master device acquires
cumulative generated output voltage from all interconnected
devices, but only its own output current.
Current values from all of the interconnected devices must be
added together in order to calculate cumulative output current.
SLP-KONSTANTER
SLP-KONSTANTER
SLP-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
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 kΩ
Slave 2
Settings
USET > Uset
master
ISET = 0 A
OUTPUT on
1 kΩ
Output
Output
Output
R
sym
R
sym
Master: SLP 120-20
U
nom
:
20 V
I
nom
:
10 A
Settings: USET:12 VISET:3 A(30%)
Slave 1: SLP 120-20 U
nom
:20 VI
nom
:10 A
Results in: Uout:12 VIout:3 A(30%)
Slave 2: SLP 120-40 U
nom
:40 VI
nom
:6 A
Results in: Uout:12 VIout: 1.8 A (30%)