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GENERAL |
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HVR Rod and Tube Resistors
are manufactured from a carefully selected mixture of clays, alumina and
carbon. After blending, the material is
extruded into the required shape and then fired,
in a controlled atmosphere, at high temperature. |
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Aluminium is then flame
sprayed onto the barrel surfaces (as standard) to provide electrical
contact.
Alternative metallised contacts and corona shielded terminals are
also available.
Rod and Tube Resistors are
available with Outside Diameters ranging from 10mm to 50mm and in Lengths
up to 600mm. |
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With High Surge Energy Rating and
Low Inductance, typical applications for HVR Rod and Tube Resistors include
Dummy Aerial Loads, Overvoltage Protection, Capacitor Discharge and Anti
Parasitic Elements in the grid and anode circuits of power valves in
induction heaters. |
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Technical Specifications |
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TYPE |
710 |
701 |
702 |
708* |
721* |
720 |
719 |
723 |
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Do (mm) |
25 |
25 |
25 |
20 |
10 |
10 |
10 |
10 |
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Di (mm) |
15 |
15 |
15 |
- |
- |
- |
- |
- |
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L (mm) |
460 |
250 |
150 |
60 - 200 |
50 - 150 |
116 |
56 |
50 |
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Lm NOM. (mm) |
25 |
25 |
25 |
10 |
10 |
10 |
10 |
10 |
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WEIGHT (g) |
295 |
160 |
95 |
38 - 130 |
7 - 23 |
18 |
9 |
7 |
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OHMS |
Min |
47 |
22 |
10 |
4R7 |
10 |
22 |
10 |
10 |
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Max |
10000 |
4700 |
2200 |
4700 |
3300 |
2200 |
1000 |
1000 |
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JOULES @ 20˚C |
45000 |
22000 |
11000 |
4500
to
20000 |
1000
to
3000 |
2600 |
1100 |
1000 |
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WATTS @ 20˚C |
150 |
90 |
55 |
18 - 80 |
10 - 30 |
20 |
10 |
10 |
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IMPULSE VOLTS
(1.2 / 50 µs) |
12Log R |
8Log R |
6Log R |
3.3Log R
to
7.5LogR |
1.6Log R
to
5LogR |
4.3Log R |
1.9Log R |
1.6Log R |
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NOTES |
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At other ambients, Ta °C,
Watts and Joules must be multiplied by the factor (220 - Ta) / 200. |
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* Types 708 and
721 are available in custom lengths (see tables below). |
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Also Available: |
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50mm Diameter
Tubes offering Higher Energy Absorption / Higher Average Power Rating. |
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25mm Diameter
Tubes manufactured to custom lengths. |
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25mm Diameter
Tubes assembled with Aluminium Ferrule Terminals. |
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Please contact
HVR Applications Department
with any specific requirements. |
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TYPE 708
RODS |
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PROD. CODE |
708A |
708B |
708F |
708D |
708G |
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Do (mm) |
20 |
20 |
20 |
20 |
20 |
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L (mm) |
70 |
100 |
125 |
150 |
185 |
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Lm NOM. (mm) |
10 |
10 |
10 |
10 |
10 |
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WEIGHT (g) |
46 |
65 |
81 |
98 |
120 |
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OHMS |
Min |
3R3 |
5R6 |
6R8 |
10R0 |
12R0 |
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Max |
1K5 |
2K7 |
3K3 |
3K9 |
5K6 |
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JOULES @ 20˚C |
5650 |
9050 |
12000 |
14750 |
18750 |
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WATTS @ 20˚C |
21 |
30 |
37.5 |
45 |
55 |
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TYPE 721
RODS |
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PROD. CODE |
721A |
721G |
721D |
721B |
721F |
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Do (mm) |
10 |
10 |
10 |
10 |
10 |
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L (mm) |
60 |
85 |
100 |
125 |
150 |
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Lm NOM. (mm) |
10 |
10 |
10 |
10 |
10 |
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WEIGHT (g) |
9 |
13 |
15 |
19 |
23 |
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OHMS |
Min |
10R0 |
15R0 |
22R0 |
27R0 |
33R0 |
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Max |
4K7 |
6K8 |
10K0 |
12K0 |
15K0 |
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JOULES @ 20˚C |
1250 |
1900 |
2500 |
3300 |
4050 |
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WATTS @ 20˚C |
10 |
13.5 |
17 |
21.5 |
25.5 |
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TERMINATIONS |
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Electrical Contacts
The standard electrical
contacts are aluminium metallised surfaces.
Alternative metallised contacts
are available in silver, brass, copper or nickel.
Corona shielded terminals are
available.
Radial wire terminations are
available on 10mm diameter rods. |
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Note :
Types 708 and 721 are available to customised
lengths within the limits shown.
Custom length tubes (Do = 25mm, Di = 15mm) and
larger Diamater Tubes (Do = 50mm) are also available. |
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ELECTRICAL PARAMETERS |
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Resistance Values
Preferred values are to the E6 series per
decade. Other resistance values may be made available upon request. |
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Resistance Tolerance
± 20% but ± 10% may be made available. |
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Temperature Coefficient - TCR
Between
- 0.8% and - 0.16% per °C rise in temperature. The higher the resistivity,
the higher the temperature coefficient. |
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Shelf Life
After 6
months storage under normal conditions the resistance change is less than ±
3%. |
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Load Life Stability
After 2000 hours continuous load producing 220 °C
surface temperature, the resistance change is less than ± 20%. |
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Inductance
This is negligible and the resistors may be
described as Non-Inductive. In practice, the inductance of connecting leads
will be greater than that of the resistor. |
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Voltage Coefficient
Maximum of - 5% / kV peak / cm, decreasing with
resistivity. |
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Power Ratings
These are determined by the maximum permissible
surface temperature of 220 °C. In free air, vertical mounting will provide
better cooling than horizontal mounting. The load ratings in the table and
the de-rating formula are for vertical mounting. Forced cooling will permit a
considerable increase in loading. |
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Environment
Air, Oil, SF6. |
