the capacitance has to be halved, and vice versa. The procedure for changing the
capacitors is given in section
0
4. Once the frequency is acceptable, turn the power knob to maximum power (fully
clockwise).
If the unit is not delivering full power and the frequency is indicated as ~135 kHz
(no limit indicator will be lit), the tank frequency is below the range of the unit.
Decrease the capacitance and return to step
1.
If the limit indicator lights up and display CURR LIMIT on LCD display, increase
the inductance of the series inductors, i.e. increase the turns of the inductors
(move towards the back of the cabinet), until the limit indicator lights up and
display FRQ LIMIT on the LCD. Next begin to decrease the inductance in small
increments by moving the shorting bars up or the turn selector bar forward (away
from cabinet back) to just get out of frequency limit at full power. See section 6.4.
If the maximum series inductance still results in a current limit, a load matching
transformer is required.
If the frequency limit occurs, continue decreasing the inductance of the series
inductors, i.e. decrease the turns of the inductors, until the FRQ LIMIT
disappears on the LCD at full power. Decrease the turns in quarter turn
increments by using the sliding bars, as described in section 6.4.
5. If the inductance changes of the previous step causes the frequency to go out of the
acceptable range, adjust the capacitance and return to step
1.
6. Increasing the series inductances until the current reading is at minimal at full power
will optimize the efficiency of the system. Highly recommended!
6.2.1. Start-frequency adjustment.
The response time of the power supply, i.e. the time from the start of the heat cycle until
full power is delivered, increases as the frequency at which power is obtained
decreases. If full power is obtained at 135kHz, the response time approaches half a
second. This is because the power supply starts at 440kHz and then needs to decrease
the frequency until power is obtained. Lowering the start frequency will decrease the
response time.
Such a function is provided for applications where the operating frequency is relatively
low and response times of less than half a second is required. By using this function the
response time for any operating frequency can be reduced to less than 100ms. Another
benefit for using the start frequency is to avoid quick current increases which can cause
nuisance current trips.
See section 5.1.6. to adjust start frequency.
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