KEPCO MST 100-2MHT, Руководство оператора

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MST-MHT SERIES 071320
3.4 OUTPUT ENABLE AND DISABLE
Enabling or disabling the output of an MST-MHT Power Module differs, depending upon
whether it is operating as a voltage source or current source. The difference is determined by
the opposite impedance characteristics of an ideal voltage vs. ideal current source. This section
defines the “disable” function in terms of ideal voltage or current source characteristics, and
details the exact method by which MST-MHT Power Modules provides the disable function.
For both voltage and current sources the “disable” condition is always represented by a “no-
load” (zero load power) impedance. Regardless of whether the MST-MHT is operating in voltage
or current mode (see PAR. 3.2), the “disable” condition must ensure that the MST-MHT provides
zero power to the load, while ensuring full compliance to the load when subsequently enabled.
The correct implementation of the disable function, whether for voltage mode or current mode,
is automatic.
The definition of an ideal voltage source is a source which will supply stable voltage (Vo) into
any load impedance within the limits of its compliance current range (RL = Vo/IMAX). For an
ideal voltage source a no-load condition is then defined as infinite impedance, since this is the
only load condition at which the delivered power (Vo x Io) is zero. MST-MHT Power Modules
provide this function by opening all power relays, thus providing an open circuit to the load from
the stabilizer output. Enabling the voltage source is accomplished by closing the appropriate
relay contacts, depending upon selected output polarity, thus connecting the stabilizer output to
the load.
The definition of an ideal current source is a source which will supply stable current (Io) into any
load conductance within the limits of its compliance voltage range (GL = Io/VMAX). For an ideal
current source a no-load condition is then defined as infinite conductance (zero impedance)
since this is the only load condition at which the delivered power is zero. MST-MHT Power Mod-
ules provide this function by closing all four power relays, thus placing a short circuit (RL=0) at
the output of the load stabilizer. While “disabled,” output current from the MST-MHT load regula-
tor continues to circulate within the power module and through the shorted power relays.
Enabling the current source is accomplished by opening the appropriate relays contacts,
depending upon the selected output polarity, thus allowing the output current to flow through the
load.
As with the output polarity reversal function described in PAR. 3.3, a “dry switching” scheme is
employed during the disable and enable functions. For both voltage and current modes of oper-
ation, the CIIL command to enable the output at the load is Close (CLS), and to disable the out-
put at the load is Open (OPN); the corresponding SCPI commands are OUTP ON and OUTP
OFF, respectively.
3.5 PARALLEL OPERATION
MST-MHT Power Modules are specifically designed for operation in parallel, either for increased
power or for fault redundancy. The output stabilizer incorporates an active load-sharing scheme
to ensure equal distribution of load current among all paralleled modules, resulting in reduced
operating stress and higher reliability. The load-share circuitry employed is a single-wire type
with the positive error sense connection providing the signal return path.
To determine the number of Power Modules needed for a specific application, the user divides
the total required load current (including any transient peaks) by the Power Module’s rated cur-
rent, rounding the result up to the next whole number if necessary. This method determines “N”,
the minimum number of power modules needed to support the load. For redundant applications
this number is increased based on the desired redundancy factor (N+1, N+2, etc.). For non-