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BL3300 SERIES MANUAL 01/28/2013
SECTION 3
OPERATION
3.7 OPERATIONAL CONSIDERATIONS
GENERAL
All BL series incorporate an input rectifier system followed by a capacitive filter. To limit the in rush current to
the unit, a soft start circuit is employed. This circuits prevents nuisance tripping of protective circuits in the
line circuits as well as reducing stress on internal components . When the unit is switched off for any reason
a period of about 30 to 60 seconds is required to allow the soft start circuit to “reset” . Failure to do so may
cause the front panel breaker of the power supply to trip repeatedly as power is reapplied. This may lead to
eventual failure of the breaker. In automated systems, a time delay relay should be considered to handle
power interruptions.
OPERATION INTO LINEAR LOADS
The BL series will provide the best overall performance into a linear load. A linear load is characterized by
that fact that its current wave shape is sinusoidal. The phase relationship between the voltage and current
may be anything between 0 and 90 degrees (leading or lagging). Some examples of linear loads are as
follows:
Most AC Motors
Power Transformers
Heating Elements
Resistors
Capacitors
Most Inductors
Incandescent Lighting ( without dimmers )
Most Solenoids
Operation into these types of loads usually cause little interaction with the output stage of the model BL3300.
The main concern with a linear load is the “in-rush” current associated with it. Most heating elements and
resistors have no in-rush concerns and usually do not present any problem for the power source. Inductive
and capacitive loads may present a special problem based on their construction and the way in which they
are energized. Motors and tungsten filament lamps also present some special “start-up” concerns. The
following is intended to give the end user some insight into applying the AC source
to these types of loads.
DRIVING REACTIVE LOADS
Capacitors and inductors are reactive in nature. If the load is applied during the peak of the AC cycle there
may be a considerable in-rush of current several magnitudes larger than the steady state current. This current
is only limited by any series resistance that may be present in the load circuit. Under the right conditions, this
could trip the overload protection circuits in the power source. Certain transformers and solenoids (inductance)
present the same problem.
Several methods can be used to prevent tripping the protection circuits in the power source . One common
method is to insert a limiting impedance in series with the load. This could be in the form of a fixed resistor
or NTC (negative temperature coefficient) thermistor. Also, zero crossing switching can be employed. The
most obvious way to prevent a high in-rush current is to apply the load with the voltage set to zero (or some
low value) and energize the load slowly by turning up the voltage.
DRIVING LAMPS
Tungsten filaments lamps, when cold, present a very low resistance. Once they are energized, their
resistance quickly climbs to it’s steady state value. This characteristic must be accounted for when driving
tungsten filament lamps. The same methods for driving reactive loads can be applied to tungsten
.
Summary of Contents for BL3300 Series
Page 9: ...3 BL3300 SERIES MANUAL 01 28 2013 ALL MANUAL ADDENDUMS WILL FOLLOW THIS PAGE ...
Page 15: ...9 BL3300 SERIES MANUAL 01 28 2013 SECTION 2 UNPACKING AND INSTALLATION ...
Page 17: ...11 BL3300 SERIES MANUAL 01 28 2013 FIGURE 2 2 ...
Page 20: ...14 BL3300 SERIES MANUAL 01 28 2013 ...
Page 33: ...3 PHASE POWER CHASSIS MECHNICAL OUTLINE ...
Page 34: ...BL3300 CONTROL CHASSIS MECHANICAL OUTLINE ...
Page 35: ...BL33XX SERIES SINGLE PHASE POWER CHASSIS OUTLINE DRAWING 19 0 TYP 17 TYP 7 0 MAX ...
Page 54: ...6 1 SECTION 6 PARTS LIST AND DRAWINGS f ...
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