InsulGard System Installation and Start Up Guideline
11
IPDS - Integrated Partial Discharge Sensors
IPDS sensors are 80pF coupling capacitors (CC) with voltage ratings from 5kV to 38kV and special protection PCB
board built in. For sensor installation:
a) Sensor must be reliably grounded.
b) Correctly connect the coaxial cable to the sensor (Figure 1-10a).
Don’t swap connection of the shield and
central wire.
c) Supplied HV jumper cable should be kept as short as possible to keep low the circuit impedance
d) Provide right distances between sensors and their jumper cables connected to different HV phases and also
to grounded surfaces. Rule of thumb: the distance should be the same as IPDS height for given voltage
class. Check clearance between signal cable and HV conductors.
e) For rotating machines, be sure to install sensors on the HV phase leads and not on the neutral side of the
winding.
RFCT Sensor - Radio Frequency Current Transformer
RFCT Sensors can be installed on the shield grounding lead of each AC power phase or one sensor on all three
phase shield grounding leads.
Install it in proper direction of the arrow on the sensor’s label to Ground. Be sure that
the wires grounding feeder shields don’t touch grounding surface before they go through the sensor (Figure 1-10b).
a.
Coax cable connection to IPDS sensor
b.
RFCT sensor installation on 3 phase ground shield
wires
Figure 1-10
RTD-6 - PD sensor (for rotating machines only)
The RTD-6 sensor uses RTDs (Resistive Temperature Detectors) installed in a rotating machine stator and work as
a local RF antenna for PD pulses. This sensor connects up to 6 RTDs to capture PD signals, which originated in a
stator winding. This sensor is designed for replacing an existing RTD terminal board and does not affect temperature
measurements.
a) Verify that the existing RTD termination box at the Motor frame is large enough to install the RTD module.
Most RTD termination boxes are large enough to accommodate the RTD Module. Mounting dimensions of
the board are:
L*W*H = 7.15” * 2.05” * 0.8”;
mounting holes have diameter 0.25” for #10 screw at 6.65” distance on the board axis;
mo
unting tabs thickness is 0.25”.
From feeders'
shields
To the Ground
Bus
Additional short
ground if original
ground is 2' or longer
To a closest
frame ground
point
Coax Cable to
a connection
box
This
Direction to
Ground
Central
conductor
Shield
These wires must not
touch ground surface
