SETPOINT MONITORS
HSP power supplies provide measurement ports which permit the user to verify the programmed output voltage and current limit points while the power supply is in an active circuit, and even when operated in a parallel/redundant configuration. These setpoint monitors access the voltage and current loop reference sources to determine the programmed values, and convert these reference levels to proportional voltages readable by the user. As the quantities measured are control circuit setpoints and not actual output measurements, the external operating conditions do not influence these measurements and they remain valid even when the power supply output is disabled; only valid source power is required.The setpoints are available at two locations on the power supply. The first is via test probe jacks on the front panel of the HSP, directly adjacent to their corresponding internal adjustment controls; the jacks are labeled VO and IMAX, with a third test point labeled COM providing access to the circuit return. The second location is the I/O connector: here, the test points are labeled VSET and ISET, and are available at pins 36 and 33, respectively, with circuit return accessed at pin 19 (-S).
Measurement quantities are defined as follows:
VO, VSET: This voltage represents 1/10 of the programmed output voltage. As an example, VSET (or VO) = 4.63V corresponds to a programmed output voltage of 46.3V ±1%. This relationship is constant, regardless of the programming range selected.
IMAX, ISET: This voltage represents the percentage of available power supply current as a percentage of rated current, with 10V corresponding to 100%; available current is defined as the maximum current limit available based on the programming range selected.
Unlike VSET, ISET is always based on a 0-10V scale, regardless of the range selected. For example, ISET (or IMAX) = 6.2V corresponds to 62% of the maximum programmable current; for the low programming range, this corresponds to 62% of the rated module current, but for the high programming range the number is 62% of 110%, or 68.2% of rated module current. If the module is HSP 5-200, for example, the programmed current limit is either 124A or 136.4A, depending on the range selection. Current setpoint monitor accuracy is ±5%.
