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BL3300 SERIES MANUAL 01/28/2013
SECTION 5
THEORY OF OPERATION
5.1 GENERAL
5.1.1
The BL series represents low cost, high performance, AC to AC power invertors. These units
provide variable output voltage and frequency from 0 to 135 Vac and 45 to 500 Hz respectively. This series
may be operated from a 120/208 Vac, 220/380 Vac 277/480 Vac, 200 Vac (Delta), or 346/600 Vac three
phase or 120Vac or 240Vac single phase input line at 50 or 60 Hertz. Other versions include higher single
phase outputs and external step-up/down output transformer options.
5.2 INPUT POWER
5.2.1
The BL series models consist of two basic sections, and input power chassis (DC power supply) and
an inverter/control chassis. The incoming line voltage is connected to the input chassis where it is applied to
a multi-pulse transformer/rectifier system. The output of the rectifier circuit is applied to a large bank of
electrolytic capacitors to provide the required filtering. The output of the power chassis is a bipolar DC voltage
of +/-250 Vdc centered around the circuit common. Additional circuitry is incorporated to provide in rush
current limiting and overload protection.
5.2.2
In rush surge limiting is provided by placing large power resistors in series with two of the input phase
voltages and the power chassis transformer primary. During power up, these resistors limit the current surge
to the filter capacitor bank. Once full voltage is reached, a relay is used to bypass the limiting resistors
allowing normal operation.
5.2.3
Over current protection of the DC supply is provided by the multi-pole input circuit breaker. Additional
protection is provided by fast acting semiconductor fuses located in the control chassis.
5.2.4
The output of the power chassis is available at a rear panel mounted terminal block. Connection to
the control chassis is afforded by supplied jumper cables. Note that the length of these cables is somewhat
critical. Do not substitute with long cables.
5.3 CONTROL CHASSIS
5.3.1
The control chassis contains the main power inverters, bias, and control circuitry. The diagram of
Figure 1 depicts the basic functional blocks. Note that in the case of the three phase units, only one phase
is illustrated as the others are identical. The circuitry is configured so that each of the three "Phase Control
Cards" plug into a "Motherboard". The output devices and output filter components are mounted on separate
assemblies.
5.3.2
Bias power for the control chassis is derived from the +250 Vdc rail. This voltage is applied to the
Motherboard. All other operating voltages are provided by the Motherboard.
5.4 MOTHERBOARD
5.4.1
The Motherboard uses a flyback type inverter to provide the following low voltage supplies.
a.
+/-15 Vdc for analog circuits
b.
+5 Vdc for metering circuits
c.
+12 Vdc for fans and relays
d.
isolated supplies for IGBT drivers
A quick indication of the supply status is provided by LEDS connected to each supply output.
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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