Theory And Troubleshooting; Input Power Section; Charging Section - PowerTec 2000C Instruction Manual

Figure 28 is a somewhat simplified schematic dia-
gram of the power section of the POWERTEC Model
2000C and the Model 3000C Brushless DC motor con-
trols. The power sections of the two controls are electri-
cally the same. The only differences are in the size and
power handling capability of the components.
The high power section is electrically isolated from
the control electronics. The only connections between the
power section and control section are two ribbon cables.

6.1 INPUT POWER SECTION

The main power is connected to the input fuses. The
line power is 3 phase AC power of 230, 380, or 460VAC.
CHECK THE CONTROL NAMEPLATE FOR THE
PROPER INPUT VOLTAGE BEFORE APPLYING POWER!
Section 2.1 lists the input power requirements. This
power must be within specified conditions (section 2.3) at
all times. Line frequencies of 48 to 62 Hertz are acceptable.
See Figure 14 on page 15.
The input fuses are a fast-acting type of fuse which
is chosen for its very high interrupting capacity (200,000
Amperes Interrupting Capacity) for ground and short cir-
cuit faults within or after the control input.
DO NOT SUBSTITUTE ANOTHER TYPE OF FUSE FOR
THE INPUT FUSES! Use only FWH type fuses or an equiva-
lently rated fuse.
When input power is applied, diodes D1 through D6,
which may be contained in a single molded block, rectify
the AC power at the input into DC power for the power bus.
The size and type of diode bridge will vary according to the
voltage and horsepower rating of the control.
Power for the low voltage transformer is tapped off
after the main fuses. The transformer, protected by F4 and
F5, is a multi-tap type which is connectible for 230, 380 and
460VAC. All the secondaries of the power transformer
connect to the Driver Board, part # 4001-144002-003.

6.2 CHARGING SECTION

Contactor CR1 is open when power is applied, and
therefore capacitor banks C1 and C2 (there may be up to 4
paralleled capacitors in each bank) charge up through
resistor Rcharge, which is located on the chassis along with
its protective fuse F6. The fuse prevents the resistor from
burning up when trying to charge a bus which won't charge.
The capacitor banks C1 and C2 may be connected in
series or in parallel. They are connected in parallel for
© copyright 1992, 1996 by Powertec Industrial
Motors

6.0 THEORY AND TROUBLESHOOTING

230VAC input units. When the unit is connected for
380VAC or 460VAC, voltage divider resistors R3 and R4
ensure that the voltage is equally divided across the 380VAC
(530VDC) or 460VAC (640VDC) bus capacitor bank.
The bus will charge up to about 90% of the nominal
value through the resistors in about 10 to 15 seconds,
depending on the voltage connection and the number of
capacitors. When the charging current through R1 drops
below a certain point, contactor CR1 will close and the
capacitors will finish charging through inductor L1.
L1 limits the rate of change of current while the
control is in operation. It also prevents the peak currents
drawn from the power line from getting too high, thereby
improving the RMS current value and resulting in a better
power factor. L1 also reduces the effects of noise, both
incoming to the control and out-going to the lines.
NOTE: These and following problems are only possible
problems - things that MAY happen due to the electrical
construction of the motor controls. They do not represent
a history of problems encountered.
POSSIBLE PROBLEM:
INPUT FUSES BLOW WHEN POWER IS APPLIED.
1. With power off, see if the charging contactor CR1 on the chassis is
stuck closed. Use an ohmeter.
2. With an ohmmeter, check the diodes D1 through D6 by checking each
line to the positive and negative terminals.
3. Watch the BUS CHARGED LED on the current controller board to see
if it comes on immediately when power is applied.
4. Check for grounded bus or motor connections.
POSSIBLE PROBLEM:
FUSES BLOW WHEN CR1 ENERGIZES.
1. Connect a voltmeter across the positive bus (+) bar and the negative
bus (-) bar on the Capacitor Board, and watch the rate of charge to see
if CR1 is pulling in prematurely. CR1 should pull in at about 90% of
nominal bus.
2. With power off (MAKE SURE CAPACITORS ARE DISCHARGED),
use an ohmmeter to determine if there is a short across the bus.
3. If the BUS LED (on the Current Controller part # 4001-141108-XXX)
stays red for more than 30 seconds, shut off the main power and connect
a voltmeter from the positive bus connection to the negative bus
connection on the Capacitor Board. Reapply power and check the
voltage.
4. The voltage across the capacitors should be nearly equal. If not, there
may be a bad capacitor, or a voltage balancing resistor (R3 or R4) may
be open.
POSSIBLE PROBLEM:
CONTROL DOES NOT POWER UP.
1. If no LED's are lit on boards, check the input fuses.
2. If no LED's are lit on the PC boards, check fuses F4 and F5.
3. If BUS LED stays red more than 30 seconds, check fuse F6.
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