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3.3.5
ENABLING/DISABLING DC OUTPUT POWER
The BOP output can be disabled (OFF) or enabled (ON) by toggling the STANDBY key in local
mode or sending the SCPI OUTPut ON or OUTPut OFF command (see PAR. B.13) via the
selected digital remote control bus (see PAR. 3.5). The behavior of the unit when disabled
depends on the Load Type setting (see PAR. 3.3.6 and Table 3-6 for details).
3.3.6
DETERMINING HOW THE UNIT RESPONDS WHEN OUTPUT IS OFF (LOAD TYPE)
The BOP supports three Load Type selections (see Table 3-6) which determine how the power
supply responds when the output is off: ACTIVE, RESISTIVE and BATTERY. (Load type CUS-
TOM (not normally active) permits customized settings to be implemented; for details contact
consult factory.) These selections are designed to provide proper operation with different load
types. It is important to note that the Load Type selection does not affect the settings of the
power supply for ON state; it only affects the main internal reference level and the protection lev-
els during the OFF state.
For inductive loads, and especially superconducting magnet type
loads, the inherent offset of the BOP in the OFF state may generate sig-
nificant current in the circuit. A properly rated switch in parallel with a
resistor must be connected between the power supply and the load.
The switch must be open and the BOP front panel LCD must read 0V,
0A before removing or installing connections between BOP and load.
ACTIVE. Active mode (default setting) is necessary for the power supply to function properly
and safely with inductive loads and constant-current-type active electronic loads. Active mode
can also be used with resistive loads. Table 3-6 indicates how the power supply responds to a
command to go from Output ON to OFF. When the output is disabled, the unit is set to voltage
mode, voltage is set to zero and both current protect and voltage limit are set to maximum.
When the unit is enabled, the pre-existing settings for voltage, current protect and voltage limit
are restored.
For both inductive loads and constant-current-type active electronic
loads when the BOP output is set to OFF, a path is provided for absorb-
ing either the energy accumulated in the reactance of the load during
the ON state, or energy delivered by an electronic load. This prevents
damage to the load and power supply as well as providing safety for
the user. However, In addition to the built-in safety features, constant-
current-type active electronic loads must be adjusted to zero and the
BOP front panel LCD must read 0V, minimum current, before handling
the power supply-to-load connections.
RESISTIVE. This mode, as the name suggests, is useful for resistive loads. Table 3-6 indicates
how the power supply responds to a command to go from Output ON to OFF.
BOP HIPWR 080709
WARNING
WARNING
3-19
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