Energy Division
Bowthorpe LV/MV
Surge Arresters
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
IEC60099-4. 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
IEC60099-4 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 manufacturing,
ISO 9001 and 14001 compliant
TRUST Bowthorpe Surge Arresters
TVC
DLA1
OCP2
Uc
4.8kV
3-29kV
3-41kV
IN
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, (UTOV / Uc)
1.5
1.43
1.35
High current short circuit
16kA
25kA
40kA
Core technology
TVC
OCP
OCP
Please contact your local sales representative for higher Uc arresters.
2
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
1
2
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.
3
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
Excellent hydrophobicity
4
Safe short circuit failure
Superior TERT performance
3
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 flashover) 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
4
Breakdown region
Protection against Lightning over-voltages
Voltage (V/mm)
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.
Pre-breakdown
region
Protection against Switching over-voltages
Rated voltage
Continuous operating voltage
20°C
120°C
60°C
Current (Amps/mm2)
High current
region
Bowthorpe EMP, TVC Transient Voltage Clampers
Application Diagram
Lightning Strike - 5 kA
HV Winding
Single / 3 Phase
Distribution Line
LV Winding
Surge Arrester
on HV side
Neutral Bushing
TVC-1
Tank of Transformer
10 Ohms
Ground at
Consumer
Premises
Ground at Pole
Mounted
Transformer
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
Bowthorpe EMP Distribution Lightning Arresters
DLA1 series
Application:
Bowthorpe DLA1 benefits:
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.
Tested in accordance with
IEC60099-4 at independent
accredited laboratories
Superior protection margins
Generic technical data:
DLA1 series
3-29kV Uc
Rated discharge current (8/20µs):
10kA
Line discharge class 1 according to
IEC 60099-4
Long duration current impulse (2000µs):
250A
High current short circuit: (pre-failing method)
(Safe non-shattering failure mode)
25kA
High-energy handling
Energy
2.9kJ/kVUc
Superior TOV performance
2 Long duration impulses:
Direct molded housing to prevent
moisture ingress
Low residual voltages
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 manufacturing,
ISO 9001 and 14001 compliant
TRUST Bowthorpe Surge Arresters
TOV of DLA1 with single shot high current prior energy
1.55
1.50
1.45
TOV Curve
1.40
Uw / Uc
1.35
1.30
1.25
1
10
100
1000
10000
Time (s)
Temperature of samples (pre-heated): 60º C according to IEC 60099-4,
Ed 2.0 2004. 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
Bowthorpe EMP Distribution Lightning Arresters
DLA1
U continuous
kV(r.m.s)
U rated
kV(r.m.s)
3
4
5
6
8
9
10
12
15
18
20
21
22
24
29
3
4
5
6
8
9
10
12
15
18
20
21
22
24
29
3.7
5.0
6.2
7.5
10.0
11.2
12.5
15.0
18.7
22.5
25.0
26.2
27.5
30.0
36.0
U residual in kV when tested
Lightning (8/20µs)
5kA
10kA
20kA
9.80
10.50
11.89
13.07
14.00
15.85
16.34
17.50
19.81
19.61
21.00
23.77
26.14
28.00
31.70
29.41
31.50
35.66
32.68
35.00
39.62
39.22
42.00
47.54
49.02
52.50
59.43
58.82
63.00
71.32
65.36
70.00
79.24
68.63
73.50
83.20
71.90
77.00
87.16
78.43
84.00
95.09
94.80
101.50
114.90
DLA1 series
to the following impulse waveforms
Steep lightning (1/20µs)
Switching (30/60µs)
10kA
125A
500A
11.49
7.63
7.97
15.32
10.17
10.62
19.15
12.71
13.28
22.98
15.25
15.94
30.64
20.34
21.25
34.47
22.88
23.90
38.30
25.42
26.56
45.96
30.50
31.87
57.45
38.13
39.84
68.94
45.76
47.81
76.60
50.84
53.12
80.43
53.38
55.78
84.26
55.92
58.43
91.92
61.01
63.74
111.10
73.70
77.00
DLA1-xxS; Standard housing parameters
DLA1
3
4
5
6
8
9
10
12
15
18
20
21
22
24
29
Impulse
voltage
1.2/50µs
(kV)
106
106
106
106
106
106
106
106
128
154
154
180
180
180
205
Power frequency
voltage withstand,
wet
(kV)
47
47
47
47
47
47
47
47
57
68
68
80
80
80
91
Flash
over
distance
(mm)
176
176
176
176
176
176
176
176
214
254
254
293
293
293
334
Creepage
Height
L
(mm)
379
379
379
379
379
379
379
379
503
629
629
755
755
755
882
(mm)
183
183
183
183
183
183
183
183
220
260
260
299
299
299
334
Creepage
Height
L
(mm)
503
503
503
503
503
503
503
503
629
755
755
882
882
882
(mm)
214
214
214
214
214
214
214
214
254
293
293
334
334
334
Tested in accordance with
IEC 60099-4, Ed 2.0 2004
L
DLA1-xxL; Extended housing parameters
DLA1
3
4
5
6
8
9
10
12
15
18
20
21
22
24
Impulse
voltage
1.2/50µs
(kV)
128
128
128
128
128
128
128
128
154
180
180
205
205
205
Power frequency
voltage
withstand, wet
(kV)
57
57
57
57
57
57
57
57
68
80
80
91
91
91
Flash
over
distance
(mm)
214
214
214
214
214
214
214
214
254
293
293
334
334
334
97mm
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
Bowthorpe EMP Open Cage Polymeric arresters
OCP2 series
Application:
Bowthorpe EMP OCP benefits:
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:
Tested in accordance with
IEC60099-4 at independent
accredited laboratories
Superior protection margins
OCP2 series
3-41kV Uc
Rated discharge current (8/20µs):
10kA
Line discharge class 2 according to
IEC 60099-4
Direct molded housing to prevent
moisture ingress
Long duration current impulse (2000µs):
530A
Low residual voltages
High current short circuit: (pre-failing method)
(Safe non-shattering failure mode)
40kA
Energy
6.0kJ/kVUc
High-energy handling
2 Long duration impulses:
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 manufacturing,
ISO 9001 and 14001 compliant
TRUST Bowthorpe Surge Arresters
TOV for OCP2 with prior energy
1.6
1.5
TOV Curve
1.4
1.3
Uw / Uc
1.2
1.1
1.0
1
10
100
1000
10000
100000
Time (s)
Temperature of samples (pre-heated): 60° C according to IEC 60099-4,
Ed 2.0 2004. 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
Bowthorpe EMP Open Cage Polymeric arresters
OCP2
U continuous
kV(r.m.s)
U rated
kV(r.m.s)
3
4
5
6
8
9
10
12
15
18
20
21
22
24
29
3
4
5
6
8
9
10
12
15
18
20
21
22
24
29
3.7
5.0
6.2
7.5
10.0
11.2
12.5
15.0
18.7
22.5
25.0
26.2
27.5
30.0
36.3
U residual in kV when tested
Lightning (8/20µs)
5kA
10kA
20kA
9.18
9.72
10.84
12.24
12.96
14.46
15.30
16.20
18.07
18.36
19.44
21.68
24.48
25.92
28.91
27.54
29.16
32.53
30.60
32.40
36.14
36.72
38.88
43.37
45.90
48.60
54.21
55.08
58.32
65.05
61.20
64.80
72.28
64.26
68.04
75.89
67.32
71.28
79.51
73.44
77.76
86.74
88.74
93.96
104.81
OCP2-xxS; Standard housing parameters
OCP2
Impulse
Power frequency
voltage
voltage withstand,
1.2/50µs
wet
(kV)
(kV)
3
145
47
4
145
47
5
145
47
6
145
47
8
145
47
9
145
47
10
145
47
12
145
47
15
165
57
18
180
70
20
180
70
21
200
80
22
200
80
24
200
80
29
230
95
Flash
over
distance
(mm)
176
176
176
176
176
176
176
176
214
254
254
293
293
293
334
OCP2-xxL; Extended housing parameters
OCP2
Impulse
Power frequency
voltage
voltage withstand,
1.2/50µs
wet
(kV)
(kV)
3
165
57
4
165
57
5
165
57
6
165
57
8
165
57
9
165
57
10
165
57
12
165
57
15
180
70
18
200
80
20
200
80
21
230
95
22
230
95
24
230
95
Flash
over
distance
(mm)
214
214
214
214
214
214
214
214
254
293
293
334
334
334
OCP2 series
to the following impulse waveforms
Steep lightning (1/20µs)
Switching (30/60µs)
10kA
125A
500A
10.10
7.37
7.76
13.47
9.83
10.35
16.84
12.29
12.94
20.21
14.75
15.53
26.94
19.66
20.70
30.31
22.12
23.29
33.68
24.58
25.88
40.42
29.50
31.06
50.52
36.87
38.82
60.62
44.24
46.58
67.36
49.16
51.76
70.73
51.62
54.35
74.10
54.08
56.94
80.83
58.99
62.11
97.67
71.28
75.05
Creepage
Height
L
(mm)
380
380
380
380
380
380
380
380
505
632
632
758
758
758
885
(mm)
183
183
183
183
183
183
183
183
220
260
260
299
299
299
340
Creepage
Height
L
(mm)
505
505
505
505
505
505
505
505
632
758
758
885
885
885
(mm)
220
220
220
220
220
220
220
220
260
299
299
340
340
340
Tested in accordance with
IEC 60099-4, Ed 2.0 2004
L
97mm
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
Bowthorpe EMP Open Cage Polymeric arresters
OCP2
U continuous
kV(r.m.s)
U rated
kV(r.m.s)
29
30
31
33
36
39
40
41
29
30
31
33
36
39
40
41
36.3
37.5
38.8
41.3
45.0
48.8
50.0
51.3
U residual in kV when tested
Lightning (8/20µs)
5kA
10kA
20kA
88.74
93.96
104.81
91.80
97.20
108.42
94.86
100.44
112.03
100.98 106.92
119.26
110.16
116.64
130.10
119.34
126.36
140.95
122.40 129.60
144.56
125.46 132.84
148.17
OCP2-xxM; Standard housing parameters
OCP2
Impulse
Power frequency
voltage
voltage withstand,
1.2/50µs
wet
(kV)
(kV)
29
204
98
30
204
98
31
228
110
33
228
110
36
250
122
39
250
122
40
250
122
41
250
122
Flash
over
distance
(mm)
339
339
378
378
418
418
418
418
OCP2 series
to the following impulse waveforms
Steep lightning (1/20µs)
Switching (30/60µs)
10kA
125A
500A
97.67
71.28
75.05
101.04
73.74
77.64
104.41
76.20
80.23
111.14
81.11
85.40
121.25
88.49
93.17
131.35
95.86
100.93
134.72
98.32
103.52
138.09
100.78
106.11
Creepage
Height
L
(mm)
970
970
1125
1125
1279
1279
1279
1279
(mm)
343
343
383
383
423
423
423
423
Tested in accordance with
IEC 60099-4, Ed 2.0 2004
L
OCP2-xxML; Extended housing parameters
OCP2
Impulse
Power frequency
voltage
voltage withstand,
1.2/50µs
wet
(kV)
(kV)
29
228
110
30
228
110
33
250
122
36
250
122
Flash
over
distance
(mm)
378
378
418
418
Creepage
Height
L
(mm)
1125
1125
1279
1279
(mm)
383
383
423
423
107mm
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
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 60071-2.
Arrester type:
DLA1 = 10kA, class 1 (3-29 kV)
OCP2 = 10kA, class 2 (3-41 kV)
b
Uc (kV)
3-29 30-41
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
55mm
M
N
55mm
Q
V
55mm
Arrester Type = Continuous Operating Voltage Uc in kV
03 04 05 06 08
09
10
12
15
18
20
21
22
24
29
30
31
33
36
39
40 41
DLA1 –
0 – 12
OCP2 –
All accessories use M12 stainless steel studs
Mounting accessories
A
B
C
N
T
55mm
Ground lead accessories
55mm
55mm
D
55mm
F
M
N
V
Additional accessory options available on request. Please contact: surgearresters@tycoelectronics.com with your
specific requirement.
11
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)330 088 0560
Fax: +44 (0)1245 808399
Email: sales@keison.co.uk
Please note - Product designs and specifications are subject to change without notice. The user is responsible for determining the
suitability of this product.