EATON ELECTRICAL
58
Predictive Diagnostics
6.2.1.1
Measuring phase shift with InsulGard
InsulGard may operate as a simple phase meter, if
PhShiFt
procedure is selected in setup mode and
Set
key is pressed.
Connections Pre-Revision 1
Phase reference signal should be temporarily connected to the terminal #12 (Humidity sensor should be
disconnected). At some rare instances InsulGard is configured for Voltage signal. Then reference signal
should be connected to the terminal #7 (marked as “PT”). In both cases, if other than coupling capacitor
on Ch1 is used common wire (ground) should be connected to the terminal #6.
Note that the terminal #12 has 1Mohm to the ground (high impedance input) and the terminal #7 has
2kOhm to the ground (low impedance input).
Note that a reference signal should not exceed 3.5VAC.
In case of PT signal is used and in order to
protect both PT output and InsulGard input make simple resistive divider circuit.
50-100
kOhm
7
5
6
8
PT
11
9
10
12
Fuse
100mAmp
50-100
kOhm
7
5
6
8
PT
11
9
10
12
Fuse
100mAmp
1-3
kOhm
PT Connection to
terminal #12
PT Connection to
terminal #7
Connections Revision 1
As it has been noted, all connections are pre-configured for using coupling capacitor on the channel 1 for
the phase shift detection. All is needed is to set switch in the sensor interface board into “Ref” position to
the right.
Note: do not forget to return it into Humidity mode after completion!
If an external signal is needed for the procedure, it should be connected to the terminal #7 and common
terminal #9. As above, the switch should be set into “Ref” position and jumper J1 (the figure 6.3a)
removed. Note that input impedance is 1Mohm and a reference signal should not exceed 6AC.
In case of
PT signal is used and in order to protect both PT output and InsulGard input make simple resistive divider
circuit made of 10kOhm and 100Ohm resistors.
Measurement
As mentioned above, in
PhShiFt
setup mode pressing
Set
key starts a phase angle measurement
between InsulGard power source voltage and AC signal brought to the InsulGard. InsulGard display will
be updated with a measured value once every 15 seconds.
Normally measured value deviates within the range of +/- 5
0
. One need to observe IG display for 1-2
minutes and derive average of displayed angles.
A measured angle is the angle between InsulGard power source voltage and signal selected for phase
reference purpose. If reference voltage is different from phase A, a correction for the difference between
reference source and the phase A should made manually. A number that represents the difference must
be added to a measured value. New number should be adjusted to 0
0
-360
0
range by adding or
subtracting 360
0
and resultant number manually entered into InsulGard. The table below shows correction
angle for most common phase reference signal options.
