While locating the ground contact point of phase - neutral fault current that is limited to approximately 2A, generating
approximately 10A pulses (approx. 1 second on, 1 second off) provides ease of measurement thus using short time
pulses is the common application in HRG systems today.
Generally measurement is performed by analogue and wide clamp ammeters.
The clamp ammeter outside the phase cable is traced until the pulse
current disappears on the analogue display.
High Resistance Grounding Sstems are economical and practical
choice especially systems under 5000 Volts.
As zero sequence (3Io) currents flow thru neutral point due to line
capacitance of cables, HGR alarm level is set to a point that is
greater than 3Io .
DISCHARGE CURRENTS
OF THREE PHASE CABLES, MOTORS AND DAMPING CAPACITORS |
NETWORK VOLTAGE (V) |
CABLE (240 mm²) 3 lo (A/km) |
MOTOR (A/1000HP) |
DAMPING CAPACITORS (A) |
240...1000 |
0.3 |
0.01 |
--- |
2400 |
1.0 |
0.10 |
0.78 |
4200 |
2.0 |
0.10 |
1.35 |
7200...12000 |
2.8 |
0.15 |
2.25 |
Hilkar HIGH RESISTANCE GROUNDING DEVICE :
- 0 - 10A analog ammeter and 0 - 250V analog voltmeter with
setting on panel
- Automatic door switch for power shut down.
- TEST BUTTON to indicate fault.
- GREEN LIGHT for normal conditions.
- INTERMITTENT ALARM and RED LIGHT during ground fault.
- PULSE/NORMAL Selector swith to magnify current and
intermittent pulse during ground fault.
- Auxilliary free contacts at PULSE and ALARM position during fault.
- Dimensions (LxWxH)= 60 x 100 x 200 cm.
- Suitable for 240....4160V three phase systems.
