Chapter 2. Theory; General Description; Theory Of Operation - Advanced Energy RFG 1251 User Manual

Theory
2

General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

GENERAL DESCRIPTION
The RFG 1251 generator is a 13.56 MHz RF generator capable of providing up to 1250 W into
Ω
a 50 , non-reactive load. The RFG 1251 generator provides high accuracy power regulation
and incorporates internal protection limits permitting safe and reliable operation. The RFG
1251 generator is certified to the CE Mark and GS Mark safety and emissions requirements.
The generator is controlled through a 25-pin analog/digital user port. The output of the
generator is regulated on forward power or delivered power (forward minus reflected) (refer to
the interface signal description for pin 8 in Chapter 4). The compact nature of the RFG 1251
generator permits it to be mounted directly on the tool.
The RFG 1251 generator is designed for use with three-phase, 208 Vac input power. The
RFG 1251 generator uses water as a cooling medium and provides control signals for
powering an externally-mounted water flow solenoid. When the RF output is disabled, the
cooling water flow may be shut off to conserve water.
A series-wired, loop-through interlock string is provided through the 25-pin User port
connector. The RF output connector has an interlock switch that is wired in series with pins on
the User port connector. The switch closes when the mating RF cable is attached. These
interlocks prevent the application of RF power in the event of abnormal system conditions.
The RFG 1251 generator contains circuitry to protect itself in the event of the following
abnormal conditions:
• High reflected power conditions. Output power fold-back (forward power limiting) occurs
under the control of the generator protection circuits.
• Excessive internal temperature (typically caused by the lack of cooling water or excessive
ambient operating temperature)
• Any combination of input ac line phase drop out
• Input line brown out (under voltage) or over voltage
THEORY OF OPERATION
Figure 2-1 and Table 2-1 outline the theory of operation.
5706058-A
RFG 1251 Generator
Theory
Chapter Chapter
2
2-1