Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Welwyn Components
•
•
•
•
Impervious lead free vitreous enamel coating
Can be supplied with fixed, adjustable,
tapped or low inductance winding
Seven termination styles with choice of
mounting arrangements
Manufactured RoHS compliant
Pb-free terminations*
* Check status of stock when ordering
General Information
Vitreous enamelled wirewound resistors are capable of
withstanding a higher dissipation size for size, than any other
protected type; this is attributable to the higher operating
temperature which the wire and enamel can withstand.
Vitreous enamel provides exceptionally good protection to the
wire element and is essentially impervious to moisture. The
resistors can safely be used in harsh environmental conditions.
The Welwyn range is based on thirteen sizes of tube, each of
which has a recommended maximum dissipation which limits
operating surface temperature to a maximum of 375°C.
The stability and high reliability of Welwyn tubular vitreous
resistors is a direct result of the best quality materials being
used in their construction.
High purity ceramic tubes have been matched with nickel
chromium resistance wires and specially formulated enamel to
ensure that the resistors can withstand repeated heat cycling
without damage.
Connections between the resistance element and end
terminations are welded; other connections are brazed.
Mounting devices are available which permit resistors to be
mounted by both ends or by one end. Single ended mounting
is recommended for applications which do not subject the
resistor to shock or vibration.
Ferrules and the F type mounting plug are anchored into the
tubes with high temperature adhesive.
Special requirements, for types or styles not described
in this brochure, will be considered for economic
quantities.
Electrical Data
Power rating at 70°C
Resistance range
Limiting element voltage
TCR (-55 to +200°C)
Resistance tolerance
Values
Thermal impedance
Operating temperature range
watts
ohms
volts
ppm/°C
%
°C/watt
°C
1605
47
1601
11
1905
16
1602
1906
1603
1604
17
22
25
35
See Table 1
See Table 1
Typically: <+75
Maximum + 200
1, 2, 5, 10
See table 1 for value restrictions
E24 preferred
See fig. 1
-55 to +375
1908
54
1607
1606
76
91
See Table 1
See Table 1
1608
115
1609
165
1600
16.5
Power rating at 70°C
Resistance range
Limiting element voltage
TCR (-55 to +200°C)
Resistance tolerance
Values
Thermal impedance
Operating temperature range
watts
ohms
volts
ppm/°C
%
Typically: <+75
1, 2, 5, 10
°C/watt
°C-55 to +375
Maximum + 150
See table 1 for value restrictions
E24 preferred
See fig. 1
Note
See Figure 1 for curves of temperature rise / watts dissipation.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data, relates to current manufacture and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
Issue E · 10.05
© Welwyn Components Limited
· Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
121
Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Welwyn Components
Electrical Data
Table 1
(continued)
*Dissipation (watts) to
produce operating
hotspot temperature (°C) of:
Ambient = 20°C
Ambient
= 70°C
Resistance range (ohms)
Limiting
element
voltage
Low inductance
winding resistance
range (ohms)
Min. res. at
Max. at
Minimum
resistance at
Max. at
any
tolerance
15k
30k
56k
43k
50k
83k
100k
100k
100k
100k
160k
180k
250k
Termination
style
Type
200
1601
1905
1600
1602
1906
1603
1604
1605
1908
1607
1606
1608
1609
5
7
7.5
8
9.5
11
15.5
21
24
34
41
52
74
300
10
14.5
15
15.5
19
22
31
41
47
66
80
101
145
375
14
20
21
22
28
32
45
59
68
95
115
145
208
375
11
16
16.5
17
22
25
35
47
54
76
91
115
165
±5%
1
1
1
1
1
1
1
1
1
1
1
1
1
±2%
15
15
15
20
20
20
20
30
30
30
30
30
35
±1%
25
30
30
25
30
30
60
40
40
50
40
50
50
C
250
-
-
500
700
850
1300
1100
1200
1300
2100
2100
3000
All others
150
450
600
350
550
750
1000
900
1000
900
1900
1800
2500
±10%
10
10
10
10
10
10
15
15
10
15
15
20
30
±5%
50
50
50
50
50
50
50
50
50
50
50
50
100
either
tolerance
1.3k
3.5k
5.0k
4.0k
5.5k
7.5k
11.5k
14k
16k
22k
32k
38k
58k
*The stated dissipation applies to resistors mounted horizontally with unobstructed bore.
Performance Data
Max
Load : 1000 hours at 70°C
Shelf life : 12 months at room temperature
Climatic
Long term damp heat
Bump and vibration
Noise (in a decade of frequency)
Pulse Handling Data
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
5.0
1.0
0.5
0.2
0.1
zero
Available by request
Typ
3.5
0.1
0.35
0.05
0.02
zero
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
122
Issue E · 10.05
Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Welwyn Components
Physical Data
Table 2 Dimensions in millimetres. See fig 2-8 for styles
A
Type
1601
1905
1600
1602
1906
1603
1604
1605
1908
1607
1606
1608
1609
max
33.0
56.1
61.5
51.0
64.3
74.5
102
89.5
102
102
166
152
216
B
max
17.5
14.5
14.5
17.5
17.5
17.5
17.5
24.0
24.0
32.0
24.0
32.0
32.0
C
max
8.2
6.55
6.55
8.2
8.2
8.2
8.2
13.2
13.2
19.2
13.2
19.2
19.2
D
nom
4.5
4.5
4.5
4.5
4.5
4.5
4.5
5.7
5.7
7.0
5.7
7.0
7.0
E
max
5.0
5.0
5.0
5.0
5.0
5.0
5.0
6.8
6.8
9.8
6.8
9.8
9.8
F
max
19.5
17.5
17.5
19.5
19.5
19.5
19.5
26.5
26.5
32.0
26.5
32.0
32.0
G
nom
15
10
10
15
15
15
15
17
17
22
17
22
22
H
±.25
3.0
3.0
3.0
3.0
3.0
3.0
3.0
4.0
4.0
6.4
4.0
6.4
6.4
M3
M3
M3
M3
M3
M3
M3
M4
M4
M6
M4
M6
M6
J
K
max
59
-
-
77
90
101
128
122
134
134
198
184
248
Terminations
Styles B, 4B, AP and AW are available in all 13 tube sizes.
Styles C, CB and CP are available in sizes 1601 to 1609
inclusive, 1906 and 1908
Lugs (Figure 2): Pb free solder coated nickel iron. Denoted
by prefix B to size reference, thus B1602
Pigtails (Figure 3): 14/.193 mm copper, 150 mm minimum
length. Denoted by prefix AP, thus AP1602
Rigid wires (Figure 4): 1.2 mm diameter tinned copper, 32
mm minimum length.
Denoted by prefix AW, thus: AW1602
Lugs with screws, nuts and washers (Figure 5): Nickel
plated brass screws and nuts. Denoted by prefix 4B,
thus: 4B1602.
Ferrule, electrically isolated (Figure 6) Connection to
resistor via Pb free solder coated nickle iron lugs. Denoted
by prefix CB, thus: CB1602.
Ferrule, electrically live (Figure 7) Nickel plated brass.
Denoted by prefix C, thus: C1602.
Ferrule, electrically isolated (Figure 8): Connection to
resistor via pigtails of 14/.193 mm copper, 150mm
minimum length. Denoted by prefix CP thus: CP1602
Marking The resistors are legend marked with type
reference, resistance value, tolerance and manufacturing
date code. Value marking conforms to IEC 62.
Solvent resistance: The vitreous coating and marking are
resistant to all accepted industrial cleaning fluids.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue E · 10.05
123
Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Adjustable Resistors
(see Figure 9)
Adjustable resistors use the same basic construction as fixed
resistors already described, and have a window in the vitreous
enamel through which contact is made to the resistive
element by a sliding contact band. The band is fitted with a
clamping screw and nut to retain it firmly in position.
The adjustable winding style has a maximum permissible hot
spot temperature of 300°C and the maximum dissipation, for
an ambient temperature of 20°C, is specified in Table 4. The
Welwyn Components
partial open winding necessitates a reduced maximum
resistance, when compared with fixed resistors, and the
resistance range is also defined in Table 4.
More than one adjusting band can be fitted, up to the
maximum number specified in Table 3.
Adjustable resistors are available in termination styles B, 4B,
AP, C, CB and CP, in sizes 1602 to 1609 inclusive and 1906
and 1908 denoted by prefix ‘V’.
Table 3
Tube
size
1602
1603
1906
1604
1605
1908
1606
1607
1608
1609
20
25
25
30
30
30
27
32
32
38
38
38
3.2
3.7
3.7
3.7
3.7
3.7
3
2
4
2
3
5
20
27
3.2
1
A mm
max.
B mm
max.
Hole C
dia. mm
Max. no of
adjusting
bands
Table 4
Max. dissipation in
20°C ambient (watts)
Type
200°C
hot spot
1602
1906
1603
1604
1605
1908
1607
1606
1608
1609
8
9.5
11
16
21
24
34
41
52
74
300°C
hot spot
15.5
19
22
31
41
47
66
80
101
145
Min. for
styles VC,
VCP
4
4
6
8
6
11
11
14
17
25
Min. for
all other
styles
3
3
6
8
6
10
9
13
16
24
1.6k
2.5k
3.0k
5.3k
4.5k
7.5k
8.1k
13.2k
15.4k
25.5k
Max. for
all styles
Resistance range (ohms)
Manufactured Values
E24 preferred
Standard Selection Tolerance ±10%
All other details of the electrical and environmental
performance of adjustable resistors are the same as for
fixed resistors.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
124
Issue E · 10.05
Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Tapped Resistors
See Figure 10
Fixed resistors can be supplied with taps to special order.
Because of the reduced winding length, the total resistance of
a tapped resistor will be less than can be offered on a fixed
resistor of the same size. The reduction is proportional to the
number of taps and Table 5 is intended as a guide.
The minimum resistance per section on all sizes is 1Ω and the
standard selection tolerance for any section is ±10%
Welwyn Components
Ordering Procedure
Enquiries for tapped resistors must state the following details:
Resistance per section
Maximum dissipation per section
Maximum operating ambient temperature
Maximum permissible dimensions if important
Type of terminations required. (See ‘Terminations’, page 3)
Resistor style or proposed method of mounting.
Table 5
Maximum*
total
dissipation
in 20°C
ambient
(watts) with
single tap
14.5
15.0
15.5
19.0
22
31
41
47
66
80
101
145
Maximum*
resistance
with single
tap
(ohms)
Maximum*
number
of taps
Type
1905
1600
1602
1906
1603
1604
1605
1908
1607
1606
1608
1609
9k
12k
9k
13k
18k
29k
34k
38k
53k
78k
93k
140k
1
1
1
1
1
2
2
2
2
4
4
4
*Maximum total dissipation assumes that this will be
evenly spread over the total element length.
Low Inductance Resistors
Ayrton-Perry wound elements are supplied for low inductance
applications. This winding style has a maximum permissible
hot spot temperature of 300°C. The maximum dissipation is
defined in Table 1 under the heading Operating hot spot
temperature of 300°C, and resistance ranges are defined in
the three right-hand columns of this table.
The recommended dissipations for each of the resistor hot
spot temperatures applies to resistors mounted horizontally. If
the bore is completely blocked a 15% derating is
recommended. However, wherever possible, resistors should
be mounted vertically with unobstructed bore.
This makes best use of the chimney effect of the heated tube
and will encourage a cooling stream of air through the bore.
Allowances must be made, when tubular resistors are mounted
in banks, for the effects produced by radiation between tubes.
Appreciable reduction of hot spot temperature can be
achieved by arranging that resistors are subjected to some
measure of forced draught. In general, it is most efficient to
extract air from the resistor enclosure and arrange that an air
inlet is adjacent to the bottom of the tubes.
If soft soldered connections are used the resistors should be derated
where applicable to limit the hot spot temperature to 300°C.
Application Notes
When cold, vitreous enamel has excellent insulation resistance.
In common with all insulants the specific resistance of the
enamel decreases with increased temperature; therefore, if
operated at any temperature approaching the maximum, the
resistor cannot be classed as an insulated type and should not
be used in contact with any conducting materials.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue E · 10.05
123
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