ioning Contact Technical Services at (800) 377-4384 with any questions.
Visit our website at www.solaheviduty.com.
35
1
Power Protection and Conditioning
Operating Characteristics of the CVS & MCR Series
Regulation
Sola/Hevi-Dutys CVS pow er con di tion ers will hold output
volt ag es to ±1.0% or less with input vari a tions as great as
±15% (115V ±15% or 120 V +10%/-20%). Units op er at ed at
less than rat ed load will maintain ap prox i mate ly ±1% regula-
tion over a wider input line volt age variation. Output meets
NEMA voltage speci cations even when input voltage drops
to 65% of nominal. The output versus input voltage re la -
tion ship for a typical CVS is show in Figure A.
Figure A: Load Variation
Note: MCR line regulations: ±3% for 60 Hz; ±5% for 50 Hz.
The typical per for manc es shown in Figure B indicate that
most of the residual changes take place near the lower
(95 V) and upper (130 V) ends of the input range. It is
possible to improve output regulation if line variations remain
within a restricted range near the center of the nameplate
range (for example, 100-120 V).
Figure B: Line Regulation
Except as noted, all characteristics of Sola/Hevi-Dutys CVS products also
apply to the MCR series.
Normally, the output voltage will rise as the load is
decreased. Typical percentages for changes in resistive
load from full to zero load as shown below.
Input Characteristics
Sola/Hevi-Duty power conditioners include a resonant
circuit that is energized whether or not it is serving load. The
input current at no load or light load may run 50% or more
of the full primary current. As a result, the tem per a ture of the
unit may rise to substantially 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, the current is always leading. The input no load
watts are about 12.5% of the VA rating.
Frequency
Output voltage varies linearly with a change of fre quen cy of
the input voltage. This change is about 1.5% of the
output voltage for each 1% change in input frequency and in
the same direction as the frequency change.
Power Factor
Sola/Hevi-Duty power conditioners regulate any power factor
load. Output voltage is a function of load current and load
power factor (see Figure C). If lower voltage under lagging
power factor is objectionable, correction may be made with
ca pac i tors at the load. Median value of output voltage will
vary from the name plate rating if the load has a power
factor other than that for which the trans form er was
designed. Load regulation will also be relatively greater as
the in duc tive load power factor is decreased (see Figure C).
However, the resulting median values of output voltage will
be reg u lat ed against supply line chang es at any rea son able
load or load power factor.
CVS
Conditioner
Rating - VA
Increase in Output
Voltage due to
Load Removal
30
3%
60 & 120
2%
250 & over
1% Contact Technical Services at (800) 377-4384 with any questions.
Visit our website at www.solaheviduty.com.
36
1
Power Protection and Conditioning
Motor Loads
Because of the fast response time of the Sola circuit, any
current-limiting characteristic must be taken into account
for transient overloads such as motor starting and solenoid
operation. In general, the Sola constant voltage regulator
must have a ca pac i ty nearly equal to the max i mum de mand
made on it, even for an instant. To determine the power
rating of the regulator, peak motor-starting current or
so le noid inrush current should be measured or power factor
cor rect ing capacitors should be used to reduce the starting
VA of the load.
Response Time
An important advantage of Solas ferroresonant trans form er
is its fast response time compared with other types of AC
regulators. Transient changes in supply voltage are usually
corrected within 1-1/2 cycles or less; the output voltage
will not uctuate more than a few percent, even during this
interval.
Figure D: Overload Performance
Figure C: Power Factor
Efficiency
The copper magnet wire and lamination material used in
Sola/Hevi-Duty ferroresonant products are selected to
achieve ef cien cies of 90% or higher. Whether or not an
external load is being served, current will be drawn from the
line whenever the primary is energized, since the capacitor
remains connected in the circuit.
Overload and Short Circuits
When the load is increased beyond the regulators rated
value, a point is reached where the output voltage sud den ly
col laps es and will not regain its normal value until the load is
partially released. Under direct short circuit, the load current
is limited to approximately 150-200% of the rated full load
value and the input watts to less than 10% of normal.
A constant voltage regulator will protect both itself and its
load against damage from ex ces sive fault currents. Fusing
of load currents may not be necessary. The actual value of
short-circuit current varies with the speci c design and
rating. Units may be operated in de nite ly at short-circuit.
This characteristic protects the unit itself as well as the load
and load circuit being served. Typical overload
per for mance is shown in Figure D.
Operating Characteristics of the CVS & MCR Series Contact Technical Services at (800) 377-4384 with any questions.
Visit our website at www.solaheviduty.com.
37
1
Power Protection and Conditioning
Temperature
Solas ferroresonant power conditioners are very stable
with respect to temperature. The change in output voltage
is only 0.025%/°C. Units are factory adjusted to +2%/-0%
of nominal, with full load and nominal input voltage. This
ad just ment to the high side of nominal is to compensate for
the natural temperature drift of about 1% that takes place
during initial turn-on or warm-up. When the unit warms up to
operating tem per a ture, the voltage typ i cal ly falls about 1%.
At a stable operating temperature, the output voltage will
change slightly with varying ambient temperatures. This shift
is equal to approximately 1% for each 40°C of temperature
change. The normal maximum temperature rise of a Sola
power conditioner may fall anywhere in the range of 40°C
to 110°C depending on the type and rating. The nominal
design ambient range is between -20°C and +50°C (-20°C
to +40°C for 70 - 1000 VA, 60 Hz portable models).
External Magnetic Field
In almost all applications, this effect may be dis re gard ed.
The exclusive Sola/Hevi-Duty wide outside leg construction
(U.S. Patent 2,806,199) reduces stray magnetic elds to a
practical minimum. On critical applications, care should be
taken in ori en ta tion of the core with respect to critical circuits
to minimize the effect of the eld.
Phase Shift
The phase difference which exists between input and
output voltages is in the range of 120 degrees to 140 de-
grees at full load. This phase difference varies with the mag-
nitude and power factor of the load, and to a lesser extent,
with changes in line voltage and load power factor.
Transient Protection
Ferroresonant power conditioners protect input transients
(caused by lightning and load switch ing) from damaging the
sensitive electronic load. A typical surge protective device
(SPD) tries to clamp a transient by diverting it to ground.
A ferroresonant power conditioner blocks the tran sient.
This block ing action is achieved by total physical separation
from input (primary) to output (sec ond ary). Because of
this difference in operation, it is dif cult to apply the same
speci cations to a ferroresonant power con di tion er. Some
parallels can be made however.
One, is that under load, the let-through voltage of a
ferroresonant power con di tion er (SPD refer to "clamping
voltage) is less than 10 V above the point where the sine
wave would normally be at any given time. The ferroreso-
nant power conditioner is an active tracking suppressor
with several advantages. The Ferro power conditioner will
not shunt the transient to the ground line as SPD devices
typically do. Shunting the transient to ground can cause the
disturbance to be transmitted to other sen si tive loads within
a facility. This can pose serious problems with elec tron ic or
microprocessor-based equip ment, especially if there is poor
grounding within a facility. Other advantages provided by fer-
roresonant power con di tion ers include noise ltering, ltering
of har mon ic distortion and protection against voltage uctua-
tions such as sags or swells. These features are not provided
by standard surge suppression devices but are often
mis rep re sent ed or misused by SPD manufacturers trying to
market their product as a Do All power quality device.
Operating Characteristics of the CVS & MCR Series