Effect Of Frequency; Response Time; Input Characteristics; Current Limitations - Emerson SolaHD MCR Hardwired Serie Mode D'emploi

MCR Hardwired Series – 50 Hz & 60 Hz
A272-282 Rev. 4 02/2020

6.5 effect of Frequency

Changes in the frequency of the supply voltage will be directly reflected in the output voltage. A change of
about 1.8% in output voltage will occur for every 1% change in input frequency, and in the same direction as
the frequency change.

6.6 Response time

An important advantage of the SolaHD principle of static magnetic regulation is its exceedingly fast response
time compared with other types of ac regulators. Transient changes in supply voltage are usually corrected
with 1-1/2 cycles or less; the output voltage will not fluctuate more than a few percent.

6.7 Input Characteristics

The MCR's transformer includes a resonant circuit, which is energized whether it is serving a load or not.
Therefore, the input current at no load is approximately 35% of the full-load level, even at light or no load.
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.

6.8 Current Limitations

When the load is increased beyond the MCR'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 twice of the rated full-load value, and the input power
to less than 10% of normal. The unit will protect both itself and its load against damage from excessive fault
currents. Fusing of load circuits is not necessary.

6.9 operation with Motor Loads

Because of the current-limiting effect described above, special attention should be given to motor
applications. In general, the regulator must have a load rating nearly equal to the maximum power drawn
during the starting cycle. This may run from two to eight times the normal (running) rating of the motor. In
doubtful cases, it is advisable to measure the actual starting current.
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