Installation manual

SAFEPATH Manual Sheet 45 of 78
Rev. C April 1999
Ground Fault Detection Sensitivity Adjustment
The resistance at which a ground fault condition will be indicated is adjustable. The ground fault detection sensitivity can be
adjusted between 40K and 500K Ohms. Selecting a high sensitivity (high resistance) will have a fast response to ground fault
conditions, but may also cause a high number of false trouble conditions. Selecting a low sensitivity (low resistance) will greatly
reduce the susceptibility to false trouble conditions, but will slow the response to ground fault conditions.
Before the following adjustment procedure is performed, all trouble conditions must be corrected (cleared) and the "GROUND
FAULT ENABLE ("EN")/DISABLE ("DIS") jumper placed in the enable position.
NOTE
: The ground fault detection sensitivity setpoint must be approved by the authorities having jurisdiction.
Adjustment Procedure
1. Disconnect the wire between the earth ground terminal on the digital voice module (see Figure 5 for DX-100 or Figure 6 for DX-
200) and earth ground.
2. Rotate the shaft of the Ground Fault Detection Sensitivity potentiometer (R517 on DX-100 or R123 on DX-200) fully counter
clockwise (see Figure 5 for DX-100 or Figure 6 for DX-200). The potentiometer is a twelve turn device, so the shaft will
probably have to be rotated a number of times. The potentiometer will make a clicking sound when it is rotated past its end
point.
3. Place a resistor with the desired setpoint value between the positive side of the input voltage of the digital voice module and
the earth ground terminal on the printed circuit board.
4. Slowly rotate the shaft of the Ground Fault Detection Sensitivity potentiometer clockwise. When a ground fault is indicated by
the trouble LED's, the sensitivity setpoint is set correctly.
5. Disconnect the resistor used to set the sensitivity level.
6. Reconnect the wire between the earth ground terminal on the printed circuit board and earth ground.