February 2001
INTELLIGENT DIRECTIONAL FAULT-CURRENT
INDICATOR FOR 10-24kV UNDERGROUND
CABLE NETW ORKS
• Detects and indicates phase
to ground and phase to phase
(PTP) faults.
• Directional indication for
phase to ground (PTG) faults.
• Insensitive to capacitive
discharge currents and
change of feeding direction.
• Internal fault counter and log.
• Multiple power-supply solutions.
• External indication unit.
• Relay output for connection to
Communication devices and
SCADA RTU’s.
CableTroll 3500 is suitable in electricity distribution networks with resistor earthed
neutral, isolated neutral as well as compensated networks (Petersen coil). State of the
art technology allowing the utilities the possibility to program the operational
parameters to suit their own demands for functionality and complexity.
Established in 1977, Nortroll has gained considerable experience within fault finding,
automation and surveillance of distribution networks.
CableTroll® 3500 Product News
Page 1
CABLETROLL 3500
CABLETROLL 3500 is used to locate short-circuit /Phase To Phase (PTP)- and earth faults/Phase To
Earth (PTG) in underground cable distribution networks. The indicator can be used in networks with
isolated or impedance earthed neutral as well as compensated (Petersen coil) networks.
The indicators are placed at substations, ringmain units or any installation where you have a cable
termination and access to capacitive test points for measuring the phase voltage.
Upon detecting a fault in the cable, the indicator gives off an intermittent red or green light-flash (LED).
One LED flashing indicating an earth-fault and both LED flashing indicating a short-circuit fault. External
indication units for mounting outside the station can be supplied as an option. The colours of the LED will
also indicate direction to the fault location for earth-faults with reference to the busbar where the indicator
is situated.
HV/MV infeed
substation
PTG
FAULT
G
RG
G
RG
G
fault
site
RG
R
red or green
light
R G
Busbar
Busbar
G
RG
R
R
G
R
PTP
FAULT
R G
R
HV/MV infeed
substation
alternating
red/green light
fault
site
Fig. 1. Indicators during a fault situation
Upon sensing an earthfault (PTG) all indicators installed on the feeder with fault, both upstream and down
stream will operate. Upon sensing a short circuit fault (PTP) only indicators installed between the feeding
transformer and the fault location will operate
CABLETROLL 3500 provides fast fault location enabling reduction in outage times. This represents
enhanced service to the customers thereby improving the quality of electricity-supply.
CableTroll® 3500 Product News
Page 2
Another important aspect of using fault indicators is that unnecessary operations of circuit-breakers and
sectionalises to locate faults are avoided. This way the indicators help to reduce wear and tear as reclosing
cycles causes stress to the switchgears.
FUNCTIONAL DESCRIPTION
CABLETROLL 3500’s fault sensing is based on analyses of the current discharge transient and the residua
voltage at the time of the fault appearance.
The fault current is picked up by three current sensors, one for each phase and the voltage is measured at
the capacitive testpoints.
Sensor principle
The processor in the Indicator uses
approx. 60ms to detect the fault. It
analyses the signals from the current
sensors and the capacitive test points
before starting indication.
I0
Detection of PTP faults is based on
Current measurement (ampermetric ).
Z
Detection of PTG is based on
Analyses of residual current and
voltage. This will tell indicators
where the earth-fault is with reference
to the busbar at the location of the
indicator.
I0
I0
Application
The application of CABETROLL 3500 usually requires no previous survey of the cable network. The
indicator can be installed:
• In general, anywhere where you have access to a cable termination and capacitive testpoints.
• In location with reclosers or sectionalises to rapidly pinpoint and isolate the fault to facilitate rapid
reconnection the healthy sections.
• In connection with remotely controlled outstations where the indicator can be connected to an RTU
giving the SCADA operators immediate information of the fault location.
CableTroll® 3500 Product News
Page 3
CableTroll 3500 Connected to a SCADA RTU:
The CT 3500 are equipped with internal relays, situated in the indicator housing, giving the possibility of four
different relay-output’s to a SCADA RTU.
The different output signals can be:
• Transient Fault in red direction
• Transient Fault in green direction
• Permanent Fault in red direction
• Permanent Fault in green direction
There is in addition an input for external reset from a SCADA RTU.
CableTroll 3500 System Overview
CableTroll 3500 Connection Overview
2
P
IC
+
_
X
↵
N O
R TR
O L
ry
CT 3500
External Indicator Unit
®
- B
V
9
a te
CAPACITIVE
TEST-POINT
CO MT ROL L 3500
S 2
R
3
CABLE ENTRYCHAMBER
CmT 3500 Infrared
Communication unit
CABLE
CT 3500
INDICATOR
CURRENT
SENSORS
TEST
4
1
2
3
RESET
The Intelligent
Fault Current Indicator
EARTHING OF
CABLE SCREEN
230V
EARTHING
OF CURRENT
SENSORS
4
SUBSTATION
EARTHING
CableTroll® 3500 Product News
Page 4
CT 3500 TECHNICAL SPECIFICATIONS
BLOCKING TIME FOR INRUSH:
5 seconds
INDICATION CRITERIA PTP (SHORT CIRCUIT) FAULT
1) Line energised for more than 5 seconds
- followed by a
2) Fault current (50Hz) exceeding a preset value (500A) within 60 ms.
INDICATION CRITERIA PTG (EARTH) FAULT
1) Line energised for more than 5 seconds
- followed by a
2) Fault current discharge transient exceeding a preset value within 60 ms.
3) 50% increase in the residual voltage
REQUIRED FAULT DURATION:
Minimum 60 ms
INDICATION:
1) Indication by high intensity LED (1Hz);
- Two colours, RED and GREEN.
The LED flashes for the elapse of the timer, until voltage is restored (if voltage reset is programmed to
ON or until the indicator is reset manually.
RESET:
1) Voltage reset, delayed 5sec. or disabled.
2) Timer reset:
LED factory set to 6 hours. (The number of hours can be changed by Nortroll personnel)
3) Manual reset reset button.
CURRENT CONSUMPTION:
Non-activated:
250 uA
IR activated:
300 uA
Flash activated:
125 mA
BATTERY:
Lithium battery; 3.6V 16.5Ah at
5mA @ 20oC, type KBB-12.
NiCd battery:
EXTERNAL DC:
External DC input 10-24 VDC
CableTroll® 3500 Product News
Page 5
AMBIENT AND STORAGE TEMP:
-40oC to + 74oC
HOUSING INDICATOR:
Body: Poly Carbonate (PC) / ABS
Front cover: Transparent Poly Carbonate/ABS, UV resistant
Mechanical strength IK o7 (6J impact)
Flame retardant grades: (V-0 UL ) 750 oC
IP-55
HOUSING EXTERNAL INDICATOR:
Body: Poly Carbonate (PC) / ABS
Front cover: Transparent Poly Carbonate/ABS, UV resistant
Mechanical strength IK o9 (6J impact)
Flame retardant grades: (V-0 UL ) 750 oC
IP-55
WEIGHT&VOLUME:
Complete box with
indicator, 3pcs sensor elements with cable and screws
Weight: 1400 grams (including 3 batteries and 3 current sensor elements)
Volume: 300x400x800 mm
Weight:
ORDERING INFORMATION:
Order nr.
Product Description
4010
4020
CT 3500 with 3 pcs of Lithium batteriesCT 3500 with 230VAC adaptor and rechargeable NiCd battery
Relay-card upgrade-kit
CmT 3500 Testing, Programming and Reading unit.
External Indicator No IR communication.
External Indicator With IR communication.
3595
3625
3626
CableTroll® 3500 Product News
Page 6