MKS 20340-341-T1, Инструкция по эксплуатации

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3 Installation
30
Series 340 Vacuum Gauge Controller
Instruction Manual - 340005 - Rev. D
3.4.1 System Ground Test Procedure
Use the following procedure to test each of your vacuum systems which incorporates an ionization
gauge.
NOTE: This procedure uses a conventional multi meter (DMM)
and a 10
Ω
, 10 W resistor.
1. Examine the grounding of both the 340 power supply and the vacuum chamber. Make sure
there is a heavy duty ground connection to all exposed conductors on the chamber and to all
exposed conductors on the vacuum chamber.
2. With the 340 VGC turned OFF, test for both DC and AC voltages between the metal parts of
the vacuum chamber and the power supply chassis.
3. If no voltages exist, measure the resistance. The resistance should not exceed 2 ohms. Two
ohms, or less, implies commonality of these grounds that should prevent the plasma from
creating a dangerous voltage between them. This test does not prove that either connection is
earth ground, only that they are the same. If more than 2 ohms is indicated, check with your
electrician.
4. If AC or DC voltages exist and are less than 10 volts, shunt the meter with a 10 ohm, 10 watt
resistor. Repeat the voltage measurement. With the shunt in place across the meter, if the
voltage remains at 83% or more of the un-shunted value, commonality of the grounds is
implied. Repeat the measurements several times to be sure that the voltage ratio is not
changing with time. This should prevent the plasma from creating a dangerous voltage
between these grounds. Make sure that no more than 10 volts exists between grounds.
5. If the voltage change in step 3 is greater than 17% due to the placement of the shunt, it
complicates the measurement. The commonality of the grounds may be satisfactory and the
coupling poor, or the commonality could be poor. Be sure to check the electrical continuity
between these two ground systems.
VOLTAGE (SHUNTED)
VOLTAGE (UNSHUNTED)
= 0.83 OR MORE