KEPCO MST Series - Manual (Page 30)

2-12
MST SERIES 061813
A practical model for a voltage-stabilized Power Module includes a series inductance represent-
ing d-c and low frequency source impedance. Load leads should have minimum voltage drops
(error sensing discussed in PAR. 2.10 below) and minimum inductance (error sensing does not
compensate for this). Similarly a model for a current stabilized Power Module includes a parallel
capacitor representing the d-c and low frequency source impedance. These considerations are
important if:
• The load is constantly changing value.
• The load is switched “on” and “off.”
• The output of the Power Module is step programmed.
• The load is reactive.
• Dynamic output response of the Power Module is of concern.
2.9 CONNECTION, GENERAL
All input and output connections between the Power Module and RA 55 Rack Adapter are made
automatically when the Power Module is fully seated in a Rack Adapter slot. Refer to the Rack
Adapter Instruction Manual for instructions on connecting RA 55 output connectors to the load,
a-c input power, and control signals.
The d-c output connector, labeled DC OUTPUT, is located on the back of chassis (Figure 2-6).
For the DC Output Connector pin designations on MST units refer to Table 2-5.
2.9.1 LOAD CONNECTION WITH LOCAL ERROR SENSING
The most basic power supply/load interface is a 2-wire connection between the power supply
output terminals and the load. This connection method employs local error sensing which con-
sists of connecting the error sense leads (pins 5 and 2) directly to the power supply output (pins
6 and 3). Its main virtue is simplicity: since voltage regulation is maintained at the power supply
output, the regulation loop is essentially unaffected by the impedances presented by the load
interconnection scheme. The main disadvantage is that it cannot compensate for losses intro-
duced by the interconnection scheme and, therefore, regulation degrades directly as a function
of distance and load current. The main applications for this method are for powering primarily
resistive and relatively constant loads located close to the power supply, or for loads requiring
stabilized current exclusively. The load leads should be tightly twisted to reduce pick-up.
TABLE 2-5. DC OUTPUT CONNECTOR PIN DESIGNATIONS
MST SIGNAL CONNECTOR PIN
Output Terminal 1 (+) 6
Output Terminal 2 (–) 3
Sense Terminal 1 (+) 5
Sense Terminal 2 (–) 2
Current Share Bus 1
Module Chassis 4
NOTE: The polarity for the terminals indicated above are for output enabled and polarity
not reversed (normal).