5 - Getting Started
12
QPX750 Instruction Manual
5.4
Meter status
The following symbols may appear in the meter display:
Mode
W
ith the output on, the mode shown will be:
CV
(Constant Voltage),
CC
(Constant Current) or
CP
(Constant Power), depending on the set limits and load conditions. The display will show
the actual output voltage and current at the terminals.
CV
Constant Voltage: Power supply will regulate at set voltage, provided the current and power
are less than
Iset
and
Plim
, respectively.
CC
Constant Current: Power supply will regulate at set current, provided the voltage and power
are less than
Vset
and
Plim,
respectively.
CP
Constant Power: Power supply will regulate at the set power, provided the voltage and current
are less than
Vset
and
Iset
respectively.
Po allows you to set voltage and currents that result in power greater than the power
curve - in this case the active mode will depend on the load.
EXAMPLE
Setting the instrument to:
Vset
36V,
Iset
36A &
Plim
750W.
Note: 36Vx36A = 1296W this is greater than max
2Ω
load: display; 36V, 18A and 648W:
CV
mode
0.5Ω
load: display; 18V, 36A and 648W:
CC
mode
1
Ω
load: display;
≈
27V,
≈
26A and 720W:
CP
mode
Protection
The OVP or OCP circuits will trip if an excessive voltage or current is accidentally set from the
front panel (via a remote-control interface) or is the result of a failure in the control circuitry of
the instrument itself. OVP will also trip if an excessive voltage is impressed across the
terminals from an external source; however, when the output is tripped off, the external
voltage will still be present, and it is up to the user to remove the source to avoid possible
damage.
OVP
Over Voltage Protection trip – If the output voltage exceeds the set OVP the output will
immediately turn off (typically within 100µs), thus avoiding damage to the circuit under test.
OCP
Over Current Protection trip - If the output current exceeds the set OCP the output is shut
down (typically within 100ms), thus avoiding damage to the circuit under test.
High Voltage Mode active- The instrument is set to the 80V range and could provide
potentially hazardous voltages.
NOTE
It is possible to set OVP or OCP below
Vset
or
Iset.
This often results in the power supply
unexpectedly turning the output off and can be used to turn the output off if the load
changes and you do not want the voltage or current to fold back.
