R E S I S T O RI ST AIN L ES S
DI P O TE N Z A S T E E L
I N ACCI AI O P O W E R
INOX RESISTORS
Resistori di messa a terra
Neutral grounding resistors
Resistori di carico
Load banks resistors
Resistori di carico per sala prove
Load banks resistors for test facilities
Resistori di carico per prove turbine a gas
Load banks for gas turbine
Resistori di filtro d armonica
Harmonic filter resistors
Resistori di avviamento e frenatura motori
Starting and braking resistors for motors
Resistenze frenatura dinamica
Dynamic braking resistors
Resistori per applicazioni ferroviarie
Resistors for railway applications
TELEMA S.P.A. Sales Office: Corso Genova, 29 20123 Milano Italy
Tel +39 02 83382.1 - Fax +39 02 83382.206
Factory: Frazione Quarto Via Salvoni, 60 29100 Piacenza Italy
Tel +39 0523 557.226 - Fax +39 0523 557.386
e-mail: info@telemait.com - http:// www.telemait.com www.telemait.com
NEUTRAL GROUNDING RESISTORS
The best passive protection against
grounding short circuit
The best way to protect transformers against ground fault
currents is to install between the star point and the earth
a resistor for the time necessary till protections are being
activated.
Such a resistor will limit the fault current to a pre-fixed
value so as not to damage the unit. Moderate fault
currents, absence of temporary excess voltage, reduction
of untimely operation of protections as well as facility in
locating failures are only some advantages with respect
to other protection systems such as reactances, isolated
neutral or direct grounding. Neutral Grounding Resistors
during heating test at CESI
During a short circuit the resistors are subject to very high power
absorption over short periods. The grounding phenomenon is thus
merely of adiabatic nature, i.e. heat is being accumulated without
external air exchange.
When designing a grounding resistor, the weight of the active part of
material (i.e. the part interested by the flow of current) is
fundamental. In fact it is the weight of the active part that determines
the quantity of energy a resistor can absorb maintaining its
temperature below a pre-fixed value.
IP54 Grounding Resistor IP 23 Grounding Resistor
10 ohms, 1500 A for 10 sec. 6 ohms, 2500 A for 10 sec.
25 /3 kV 24/3 kV
TELEMA S.P.A. Sales Office: Corso Genova, 29 20123 Milano Italy
Tel +39 02 83382.1 - Fax +39 02 83382.206
Factory: Frazione Quarto Via Salvoni, 60 29100 Piacenza Italy
Tel +39 0523 557.226 - Fax +39 0523 557.386
e-mail: info@telemait.com - http:// www.telemait.com www.telemait.com
NEUTRAL GROUNDING RESISTORS
When designing each resistor, TELEMA aims to maximise the
weight of active material in function of the maximum temperature
required.
As TELEMA can select from two different type of elements: the HPR
and the HPRS at a width up to 4 mm and in various qualities of
stainless steel.
The solution studied on purpose for every single application will
meet any individual requirement of Customer, particularly with
regard to current, resistor value, temperature, variation of resistance
between cold and hot conditions and environmental conditions.
TELEMA NEUTRAL GROUNDING RESISTORS range from class IP23 Grounding Resistor
3,6 KV to 72,5 KV with current at several thousand amperes and 6,4 ohms 600 A for 30 sec.- 6,6 /3 kV
chassis protection from IP 23 to IP 55, the latter being realised with equipped with off-load switch
special filters which permit the necessary air circulation also in
presence of reduced continuous current.
These resistors can incorporate off-load switches, load-break
switches, vacuum contactors, CT, VT, etc.
As standard, TELEMA Neutral Grounding Resistors are built and
tested to the requirement of American National Specification
Requirements, Terminology and Test Procedure for Neutral
Grounding Devices, IEEE 32-1972
All manufacture takes place in our modern purpose-built factory
operating to ISO 9001 quality standard.
For many rating and designs temperature rise type test
in accordance with IEEE 32 have been carried out at
independently certified test houses. Copies of these
certificates are available.
IP 23 Grounding Resistor
10,06 ohms, 660 A for 10 sec. - 11,5 /3 kV
equipped with medium voltage current transformer
IP 54 Grounding Resistor IP23/IP54 Grounding Resistor
57,7 ohms 300 A for 10 sec. - 30 /3 kV 20 ohms, 100 A for 5 sec. - 3,6/3 kV
equipped with incoming bushing insulator and 2 current transformer equipped with load-breack switch
TELEMA S.P.A. Sales Office: Corso Genova, 29 20123 Milano Italy
Tel +39 02 83382.1 - Fax +39 02 83382.206
Factory: Frazione Quarto Via Salvoni, 60 29100 Piacenza Italy
Tel +39 0523 557.226 - Fax +39 0523 557.386
e-mail: info@telemait.com - http:// www.telemait.com www.telemait.com
NEUTRAL GROUNDING RESISTORS
FOR MOBILE SUBSTATIONS
Modular design to meet small space requests
The reduced space at disposition on mobile substations
required modular design.
The TELEMA Neutral Grounding Resistors are the best
suitable solution for such installation:
FEATURE
No temporary over-voltages
Rapid cooling after fault
Ease of installation
Maintenance free
Traction-based designs
Stainless steel construction
BENEFIT
Compact space-saving designs
Reliable and robust during transportation
Suitable for tropical, marine and desert environments
IP23 Neutral Grounding Resistor IP21 Grounding Resistor
4,7 ohms 400 A for 10 sec.- 3,3 /3 kV 12,7 ohms 500 A for 10 sec.- 11/3 kV
equipped with off-load switch
IP54 Neutral Grounding Resistor
72 ohms 300 A for 10 sec.- 33 /3 kV
equipped with 2 current transformers
TELEMA S.P.A. Sales Office: Corso Genova, 29 20123 Milano Italy
Tel +39 02 83382.1 - Fax +39 02 83382.206
Factory: Frazione Quarto Via Salvoni, 60 29100 Piacenza Italy
Tel +39 0523 557.226 - Fax +39 0523 557.386
e-mail: info@telemait.com - http:// www.telemait.com www.telemait.com
