Energy Division. Bowthorpe LV/MV Surge Arresters

Transcription

1 Energy Division Bowthorpe LV/MV Surge Arresters

2 Bowthorpe EMP LV/MV surge arresters OCP, Open Cage Polymeric series Bowthorpe pioneered the development of polymeric housed surge arresters in the early 1980's and since 1986 have a proven service experience across the globe, operating in the worlds toughest environments. Bowthorpe OCP silicone surge arresters have been designed and tested to meet our customers toughest environmental conditions and to meet the requirements of IEC Our gapless zinc oxide polymeric arresters have been in service since 1994 and now the OCP ranges builds on this experience and know how. OCP is the latest gapless, zinc oxide arrester family from Bowthorpe. The OCP development was based on 25 years of internal experience in arrester design and manufacture within the Tyco Electronics Energy Division. The final OCP qualification was performed in independent laboratory facilities in Europe. OCP cores are manufactured using superior ZnO varistors, which display excellent thermal and current handling characteristics due to the guaranteed homogeneity of the varistor volume. This superior thermal behavior yields products with: Excellent TOV performance. Safe, non-shattering failure in the short circuit test by pre-failing to higher fault currents. High energy handling capability. Bowthorpe DLA/OCP benefits: Tested in accordance with IEC at independent accredited laboratories Superior protection margins Direct molded housing to prevent moisture ingress Low residual voltages High-energy handling Superior TOV performance Safe non-shattering short circuit behavior to higher current levels Maintenance free Hydrophobic silicone housing: (Tracking and erosion resistant) Excellent cantilever and tensile performance Excellent mechanical, vibration and impact withstand capability Quality design and manu facturing, ISO 9001 and compliant TRUST Bowthorpe Surge Arresters TVC DLA1 OCP2 Uc 4.8kV 3-29kV 3-41kV I N 5kA 10kA 10kA Long duration energy (2 shots / kj/kv Uc) N/A 2.9 kj/kv Uc 6.0 kj/kv Uc Long duration waveform 250A / 2ms 250A / 2ms 530A / 2ms 10 second TOV, (U TOV / Uc) High current short circuit 16kA 25kA 40kA Core technology TVC OCP OCP Please contact your local sales representative for higher Uc arresters. 2

3 At the core of the Bowthorpe OCP design is our improved ZnO varistor disk, which has superior thermal and electrical characteristics and stability. The resulting new varistor and OCP design combination has resulted in superior energy handling and TOV performance. The construction of the OCP design comprises of: 1 ZnO, (Zinc Oxide) varistors 2 Bowthorpe proprietary silicone housing 3 Flame retardant FRP structure 4 Corrosion resistant aluminium fittings The crimped structural construction ensures light weight product with optimal mechanical strength. The manufacturing process ensures void free construction and optimum interface sealing. This is achieved by bonding the silicone housing directly to the ZnO discs and aluminium fittings using a Bowthorpe proprietary bonding solution The silicone housing was developed using the knowledge accumulated over 35 years of internal materials science expertise and experience, resulting in an optimum shed profile and a material with excellent tracking and erosion resistance. Features of our new hydrophobic silicone OCP design are: Alternating sheds for superior pollution flash over resistance Superior TERT performance Constant voltage: 4.5kV, >360min - Stepped voltage: >300min - All eventual failures by erosion only, ie no tracking in step voltage test Housing tested to IEC 1000hr salt fog test 4 Excellent hydrophobicity Safe short circuit failure Superior TERT performance 3

4 Bowthorpe EMP, TVC Transient Voltage Clampers Introduction In the UK where severe lightning is often accompanied by poor pole earthing resistance, the secondary LV distribution system is subjected to high voltage surges due to lightning current seeking alternate ground paths through the low-voltage circuits. The typical mode of failure of a pole mounted transformer is for the low voltage winding to flash over to the transformer tank due to the relatively high voltage developed across the pole earth resistance. The high voltage arrester does not prevent this type of failure. However, to remove this source of failure (or back flash over) a TVC may be placed between the neutral bushing and the tank. Background Construction Transient Voltage Clampers are designed under the same principle as LV voltage surge arresters; however applications are more specific. M 12 Stainless Steel Termination What is a Transient Voltage Clamper, TVC? A TVC is used to protect against the internal failure of a pole mounted transformer (PMT) due to back flashover between the transformer tank and the LV winding bushing. A back flashover on a PMT will cause permanent damage to the transformer internal solid insulation. Zinc Oxide Varistor Core Conditions of Use? 1) TVC s are useful when there is very high resistivity pole grounding conditions e.g. hot, sandy, rocky ground. Under these soil conditions an earth resistance of 10 ohms or less may be difficult to achieve; resistance maybe variable throughout the year. 2) TVC s are useful when the LV earth downstream from the PMT is lower than at the pole earth resistance. 3) Best used in conjunction with HV and LV surge arresters (cannot be used instead). UV Stable Tracking Resistant Housing Current-voltage characterisitc for Zno varistor Principle of Operation TVCs incorporate a gapless metal oxide varistor, MOV design that under steady state conditions maintains the line-to-ground voltage across the TVCs terminals. When overvoltages occur, the TVC conducts current to earth, limiting the overvoltage to below the required protection levels. Upon passage of the overvoltage condition, the TVC returns to a highly non-linear steady state condition that conducts very minimal 10 s of Hz power current. Voltage (V/mm) Pre-breakdown region Protection against Lightning over-voltages Protection against Switching over-voltages 20 C 60 C 120 C Breakdown region Continuous operating voltage Current (Amps/mm 2 ) Rated voltage High current region 4

5 Bowthorpe EMP, TVC Transient Voltage Clampers Application Diagram Lightning Strike - 5 ka HV Winding LV Winding Single / 3 Phase Distribution Line Surge Arrester on HV side Neutral Bushing TVC-1 Tank of Transformer 10 Ohms Ground at Pole Mounted Transformer Ground at Consumer Premises Example Problem: A moderate lightning current of 5kA flowing to earth into a resistance of 10 ohms will raise the tank of the transformer to 50kV as V = IR. Typically the impulse breakdown voltage of the LV winding to the transformer case is 30kV. The tank voltage due to 10 ohms earth resistance can cause a breakdown between the tank and a low voltage bushing of the transformer. Any back flashover will drive high current through the low voltage windings when striking the phase connections. These high currents are driven by the power frequency flow current. Solution: To remove the back flashover a suitable device must be connected between the neutral bushing and the tank of the transformer, hence a TVC should be installed. In order to be compatible with standard auto recloser operations in the event of a fault, the device must be able to withstand the phase to earth voltage for at least 10 seconds. LV and HV surge arresters cannot be used instead of a TVC. LV Surge arresters: The LV arrester should be used in lightning prone exposed areas to give additional protection. They should be installed on the low voltage system, on the first pole down stream from the transformer. HV Surge arresters: The HV arrester should be fitted to the high voltage bushings (connections under 300mm in length to limit voltage drop). The installation of the HV arrester prevents damage to the insulation on the HV winding and the transformer case. Note: The HV arrester will not stop back flashovers across the low voltage bushings, but will limit the power follow-current, hence this is the reason why TVC s should be used. Tips: To reduce the voltage on the tank of the transformer, it is advisable to have low values of earthing resistance connected to the tank, approximately 5 ohms or less. To achieve an optimum overvoltage protection, connecting leads should be as short as possible. 5

6 Bowthorpe EMP Distribution Lightning Arresters DLA1 series Application: Protection of MV networks and equipment from lightning and switching surge related over-voltages in areas with relatively high iso-keraunic levels. Suitable for both outdoor and indoor use to protect transformers and cable end terminations. Generic technical data: DLA1 series Rated discharge current (8/20µs): 3-29kV Uc 10kA Line discharge class 1 according to IEC Long duration current impulse (2000µs): 250A High current short circuit: (pre-failing method) 25kA (Safe non-shattering failure mode) Energy 2 Long duration impulses: 2.9kJ/kVUc Bowthorpe DLA1 benefits: Tested in accordance with IEC at independent accredited laboratories Superior protection margins Direct molded housing to prevent moisture ingress Low residual voltages High-energy handling Superior TOV performance Safe non-shattering short circuit behavior to higher current levels Maintenance free Hydrophobic silicone housing: (Tracking and erosion resistant) Excellent cantilever and tensile performance Excellent mechanical, vibration and impact withstand capability Quality design and manu facturing, ISO 9001 and compliant TRUST Bowthorpe Surge Arresters TOV of DLA1 with single shot high current prior energy TOV Curve Uw / Uc Time (s) Temperature of samples (pre-heated): 60º C according to IEC , Ed TOV Curve applies to an arrester which has a pre-stress applied prior to TOV verification. This pre-stress is equivalent to one high current impulse as per the operating duty test. Uw = TOV withstand voltage; Uc = continuous operating voltage 6

7 Bowthorpe EMP Distribution Lightning Arresters DLA1 series DLA1 U continuous U rated U residual in kv when tested to the following impulse waveforms kv(r.m.s) kv(r.m.s) Lightning (8/20µs) Steep lightning (1/20µs) Switching (30/60µs) 5kA 10kA 20kA 10kA 125A 500A DLA1-xxS; Standard housing parameters DLA1 Impulse Power frequency Flash Creepage Height voltage voltage withstand, over L 1.2/50µs wet distance (kv) (kv) (mm) (mm) (mm) Tested in accordance with IEC , Ed L DLA1-xxL; Extended housing parameters DLA1 Impulse Power frequency Flash Creepage Height voltage voltage over L 1.2/50µs withstand, wet distance (kv) (kv) (mm) (mm) (mm) mm 119mm Notes: Mechnical strength data: Cantilever Nm 250 Tensile kn 2 Torque Nm 50 For accessory and ordering information, please refer to page 11 7

8 Bowthorpe EMP Open Cage Polymeric arresters OCP2 series Application: Protection of MV networks, sensitive equipment and substations from lightning and switching surge related over-voltages in areas with relatively high iso-keraunic levels. Generic technical data: OCP2 series Rated discharge current (8/20µs): 3-41kV Uc 10kA Line discharge class 2 according to IEC Long duration current impulse (2000µs): 530A High current short circuit: (pre-failing method) 40kA (Safe non-shattering failure mode) Energy 2 Long duration impulses: 6.0kJ/kVUc Bowthorpe EMP OCP benefits: Tested in accordance with IEC at independent accredited laboratories Superior protection margins Direct molded housing to prevent moisture ingress Low residual voltages High-energy handling Superior TOV performance Safe non-shattering short circuit behavior to higher current levels Maintenance free Hydrophobic silicone housing: (Tracking and erosion resistant) Excellent cantilever and tensile performance Excellent mechanical, vibration and impact withstand capability Quality design and manu facturing, ISO 9001 and compliant TRUST Bowthorpe Surge Arresters TOV for OCP2 with prior energy TOV Curve Uw / Uc Time (s) Temperature of samples (pre-heated): 60 C according to IEC , Ed TOV Curve applies to an arrester which has a pre-stress applied prior to TOV verification. This pre-stress is equivalent to two long duration current impulses having duration of 2000µs and total energy equal to 6.0 kj/kv Uc. Uw = TOV withstand voltage; Uc = continuous operating voltage 8

9 Bowthorpe EMP Open Cage Polymeric arresters OCP2 series OCP2 U continuous U rated U residual in kv when tested to the following impulse waveforms kv(r.m.s) kv(r.m.s) Lightning (8/20µs) Steep lightning (1/20µs) Switching (30/60µs) 5kA 10kA 20kA 10kA 125A 500A OCP2-xxS; Standard housing parameters OCP2 Impulse Power frequency Flash Creepage Height voltage voltage withstand, over L 1.2/50µs wet distance (kv) (kv) (mm) (mm) (mm) Tested in accordance with IEC , Ed L OCP2-xxL; Extended housing parameters OCP2 Impulse Power frequency Flash Creepage Height voltage voltage withstand, over L 1.2/50µs wet distance (kv) (kv) (mm) (mm) (mm) mm 119mm Notes: Mechnical strength data: Cantilever Nm 350 Tensile kn 2 Torque Nm 50 For accessory and ordering information, please refer to page 11 9

10 Bowthorpe EMP Open Cage Polymeric arresters OCP2 series OCP2 U continuous U rated U residual in kv when tested to the following impulse waveforms kv(r.m.s) kv(r.m.s) Lightning (8/20µs) Steep lightning (1/20µs) Switching (30/60µs) 5kA 10kA 20kA 10kA 125A 500A OCP2-xxM; Standard housing parameters OCP2 Impulse Power frequency Flash Creepage Height voltage voltage withstand, over L 1.2/50µs wet distance (kv) (kv) (mm) (mm) (mm) Tested in accordance with IEC , Ed L OCP2-xxML; Extended housing parameters OCP2 Impulse Power frequency Flash Creepage Height voltage voltage withstand, over L 1.2/50µs wet distance (kv) (kv) (mm) (mm) (mm) mm 137mm Notes: Mechnical strength data: Cantilever Nm 350 Tensile kn 2 Torque Nm 50 For accessory and ordering information, please refer to page 11 10

11 Bowthorpe EMP OCP2 and DLA1 accessories OCP2 and DLA1 series naming and order query description: Example: OCP = Open Cage Polymeric OCP2 12S MEL For installation clearances phase-phase (a) and phase-ground (b) please refer to IEC Arrester type: DLA1 = 10kA, class 1 (3-29 kv) OCP2 = 10kA, class 2 (3-41 kv) b Uc (kv) Standard creepage S M Extended creepage L* ML** * available up to Uc = 24 kv **available up to Uc = 36 kv a a Accessory selection M = Mounting bracket E = Earth connection L = Line connection Line lead accessories F M N Q V Arrester Type = Continuous Operating Voltage Uc in kv DLA OCP2 All accessories use M12 stainless steel studs Mounting accessories A B C N T Ground lead accessories D F M N V Additional accessory options available on request. Please contact: surgearresters@tycoelectronics.com with your specific requirement. 11

12 Thank you for reading this data sheet. For pricing or for further information, please contact us at our UK Office, using the details below. UK Office Keison Products, P.O. Box 2124, Chelmsford, Essex, CM1 3UP, England. Tel: +44 (0) Fax: +44 (0) Please note - Product designs and specifications are subject to change without notice. The user is responsible for determining the suitability of this product.