Valleylab Force FX Testing procedure

Valleylab Force FX periodic testing

• Electrosurgery

The passage of
high frequency
electrical current
through tissue to
create a desired
clinical effect.

2/7/2009 1

What tests should be done?

1. Output tests in each different mode;

cut, coag and bi-polar.

2. REM high and low trip points

3. RF Leakage test

2/7/2009 2

Different loads for different modes.

Usually bi-polar mode is tested at 100 ohms load,
cut mode at 300 ohms and coagulation mode at

500 ohms. Measure the current, not the watts. RF
power output circuitry is 1 to 6 N channel
MOSFET’s in parallel. With age and thermal
damage, they begin to fail and the output voltage
drops. Circuitry compensates by increasing the
current thru the MOSFET’s. Current times voltage
equals wattage. Measuring wattage will not detect

2/7/2009

the drop in voltage, but measuring current will
detect the voltage drop. Valleylab specifically
states to test for current under specified load.

3

ESU Math, not quite rocket science

√ Watt setting of ESU / Load setting of tester =

desired test result

Bi-Polar 10 Watts

√ 100 Ω

Coag 30 W

√ 500 Ω

Cut 75W

√ 300 Ω

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= √.1= .316 amp = 316 mA

= √0.06 = .245 A = 245 mA

= √.25 = .5A = 500mA

4

REM testing

•Testing must be done with the middle

pin of the r.e.m. connector present.
Without the pin, the e.s.u. switches to
non r.e.m. circuitry.

•If an e.s.u. is sent to mfr. for repair

with a r.e.m. fault, testing must be done
with the actual patient pad.

•Normal power output testing bypasses

r.e.m. circuitry.

2/7/2009

5

ESU Vocabulary page one

1. Current

The number of electrons moving past a given point per second,
measured in amperes.

2. Current Density

The amount of current flow per unit of surface area; current
concentration directly proportional to the amount of heat generated.

3. Current Division

Electrical current leaving the intended electrosurgical circuit and
following an alternate path of least resistance to ground; typically the
cause of alternate site burns when using a grounded generator.

4. Cut

A low-voltage, continuous waveform optimized for electrosurgical
cutting.

5. Cutting

Use of the cut waveform to achieve an electrosurgical effect that
results from high current density in the tissue causing cellular fluid to
burst into steam and disrupt the structure. Voltage is low and current
flow is high.

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ESU Vocabulary page two

1. Desiccation

The electrosurgical effect of tissue dehydration and protein
denaturation caused by direct contact between the
electrosurgical electrode and tissue. Lower current
density/concentration than cutting.

2. Diathermy

The healing of body tissue generated by resistance to the flow
of high-frequency electric current.

3. Direct Coupling

The condition that occurs when one electrical conductor (the
active electrode) comes into direct contact with another
secondary conductor (scopes, graspers). Electrical current
will flow from the first conductor into the secondary one and
energize it.

4. Direct Current

A flow of electrons in only one direction.

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ESU Vocabulary page three

1. Fulguration: Using electrical arcs (sparks) to coagulate

tissue. The sparks jump from the electrode across an air gap
to the tissue.

2. Generator: The machine that coverts low-frequency

alternating current to high-frequency electrosurgical current.

3. Ground, Earth Ground: The universal conductor and

common return point for electric circuits.

4. Grounded Output: The output on a electrosurgical

generator referenced to ground.

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ESU Vocabulary page four

• Impedance: A form of electrical resistance observed in an

alternating current that is analogous to the classic electrical
resistance that occurs in a direct current.

• Insulation Failure: The condition that occurs when the

insulation barrier around an electrical conductor is breached.
As a result, current will travel outside the intended circuit.

• Isolated Output: The output of an electrosurgical generator

that is not referenced to earth ground.

• Leakage Current: Current that flows along an undesired

path, usually to ground; in isolated electrosurgery, RF current
that regains its ground reference.

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ESU Vocabulary page five

• Monopolar Output: A grounded or isolated output on an

electrosurgical generator that directs current through the patient
to a patient return electrode.

• Patient Return Electrode (PRE): A conductive plate or pad

(dispersive electrode) that recovers the therapeutic current from
the patient during electrosurgery, disperses it over a wide
surface area, and returns it to the electrosurgical generator.

• Power: The amount of heat energy produced per second,

measured in watts.

• Power Efficiency Rating (PER)

A measure of the ability of an electrosurgical generator to
accurately deliver the selected power into a wide range of tissue
types.

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ESU Vocabulary page six

• Radio Frequency (RF): An electrical current that alternates the

poles in the radio frequency range (300 kHz–36 Hz); the high­frequency current used in electrosurgery.

• Resistance

The lack of conductivity or the opposition to the flow of electric
current, measured in ohms.

• Voltage

The force that pushes electric current through
impedance/resistance; electromotive force or potential
difference expressed in volts.

• Watt

The unit of measurement for power.

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Test jigs used for preventative maintenance

• Calibrated ESU analyzer

• Return/dispersive/patient cable

• Active/output cable

• Variable 1 to 150 ohm resistor

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Preventative Maintenance

Factory recommended schedule every 6 months refer to p 5-19, 5-24

Bipolar output test (page 5-18)

1.Set analyzer load resistance to 100

ohms.

2.Set bipolar power to 10.

3.Press footswitch and measure current in

all 3 modes. (Current delivered should
be 315 mA +/- 24 mA rms)

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Cut mode output test (page 5-19)

1. Set the analyzer load resistance to 300

ohms.

2. Set CUT power to 75 watts.

3. Press CUT footswitch and measure current
in the Pure, Low & Blend modes. (Current
delivered should be 499 mA +/- 38 mA.)

4. Repeat this test on the MONOPOLAR 2
using a hand piece.

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Coag output test ( page 5-20)

1. Set the analyzer load resistance to 500

ohms.

2. Set CUT power to 75 watts.

3. Press CUT footswitch and measure

current in the Pure, Low & Blend modes.
(Current delivered should be 245 mA +/­19 mA.)

4. Repeat this test on the MONOPOLAR 2

using a hand piece.

Comment to previous page:
According to the service manual the

settings should be: 80W (Low, Med,
High), 500ohms, 400mA +/-28mA.

Return Electrode Monitoring testing

1. Set var. resistor to 120 ohms and

connect to REM jack.

2. Slowly increase resistance until led turns

RED and alarms sounds, record trip
point. (135 =/- 5 ohms)

3. Disconnect, set to 20 ohms, connect.

4. Slowly decrease resistance until red led

2/7/2009

and alarm, record trip point. (3-6 ohms)

16

RF Leakage Testing

refer to page 5-23 “Checking monopolar High Frequency leakage current”

1. Set load to 200 ohms, set cut to 300

watts & pure mode, set coag to 120
watts and spray mode.

2. Activate footswitch in 4 different

settings: Open/Closed and
Active/Dispersive

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3. Record highest current, should not

exceed 150 mA

17

If High Frequency leakage is high:

1. Check REM pad socket connector

2. P.N. S202701854, $160

3. Compare your result with past tests

and other similar units