Operating & Service Instructions

50 Hz Mini/Micro
Computer Regulator (MCR) Series
Installation and Operation Manual
Contact Technical Services at [phone] with any questions.
Fax-on-Demand: [phone], Document #: 8412
14
Use with Switchmode Power Supplies
If a CVS transformer is used as a source for a switchmode power supply, a
slight amount of ringing may be noticed on the sinewave output of the CVS at
half cycle intervals for a short duration. This ringing occurs at the point when
the switchmode power supply current demand drops to zero. The ringing
should not be a cause for concern since it is of relatively low magnitude and
frequency. The CVS has been tested with a variety of switchmode power
supplies and it has been determined that the ringing never affects the DC
outputs, nor does it degrade the components of any switchmode power
supply.
Effect of Temperature
The output voltage will show a small change as the unit warms up to stable
operating temperatures at a constant ambient temperature. This change may
be about one or two percent depending on the unit’s VA rating. At a stable
operating temperature, the output voltage will change slightly with varying
ambient temperature. This shift is approximately one percent for each 40°C
of temperature change.
Response Time
Transient changes in supply voltage are usually corrected within 1-1/2 cycles
or less; the output voltage will not fluctuate more than a few percent.
Input Characteristics
The regulator transformer includes a resonant circuit that is energized
whether it is serving a load or not. Therefore, the input current at no load is
approximately 35% of the full-load primary current. Input power factor will
average 90-100% at full load but may drop to about 75% at half load and
25% at no load. In any case, it is always leading.
Current Limitation
When the load is increased beyond the regulator’s rated value, a point is
reached where the output voltage suddenly collapses and will not regain its
normal value until the load is partially released. Under short-circuit
conditions, the load current is limited to approximately 150% of the rated
full-load value and the input power to less than 10% of normal. The regulator
will protect both itself and its load against damage from excessive fault
currents. Fusing of load circuits is not necessary.