WELWYN WDBR_13

Ultra Low Profile
Power Resistors
WDBR Series
· Ultra low profile thick-film on steel
· 500W to 7kW peak power
· Single fixing heatsink mountable
· Ideal for dynamic braking, inrush limit and
snubber circuits
Choice of flying lead, push-on or solder terminations
Low inductance design
High isolation, even after failsafe overload fusing
RoHS compliant, non-flammable construction
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Electrical Data
WDBR1/2
Resistance range
ohms
WDBR1
12, 15, 20, 22, 25,
47, 50, 100
WDBR2
WDBR3
WDBR5
WDBR7
12, 15, 20, 22, 25, 47, 50, 100, 150
Resistance tolerance
%
1
kW
0.5
1.5
2.0
3.5
5.0
7.0
W
160
180
200
260
270
280
W
300
700
780
900
1000
1490
<4
<5
<6
Pulse power rating
Power rating on heatsink 2
Power rating on fan-cooled heatsink 3
TCR
10
ppm/°C
Maximum element temperature
Ambient temperature range (heatsink)
Dielectric withstand 4
+500 to +600
°C
365
°C
-55 to +200
V (dc/ac peak)
Inductance (typical)
2500
μH
<3
Notes:
1. For details of pulse condition see Fig. 1 in Performance Data.
2. Mounted on a 0.53°C/W heatsink with no forced air cooling, air temperature 25°C.
3. Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C.
4. Based on 100% production test, duration 2s minimum
Physical Data
Dimensions in mm, weight without terminations in g
D
a
L ±0.1 W ±0.1 t ±0.1 ØD nom a nom b nom c nom Wt. nom
WDBR1/2
31.9
28.1
2.2
7.5
3.1
4.3
6.5
WDBR1
49.3
35.9
3.2
3.2
11.2
6.2
12.6
WDBR2
61
40.6
4.7
13.0
5.8
17.1
WDBR3
101.6
70
13.5
22.0
10.2
50.8
WDBR5
122
70
14.0
23.8
7.4
60.7
WDBR7
152.4
101.6
0.9
5.3
1.5
15.0
51.3
9.2
181.8
c
b
W
L
Substrate thickness = t
Fixing hole is located centrally except on WDBR1/2 where the dimension from
the edge by the terminations to the mounting hole centre is 16.68mm
Construction
A high integrity dielectric layer is applied to a machined
stainless steel substrate. Thick-film conductor and resistor
patterns are printed and fired, then protected with a high
temperature overglaze. The termination pads are tinned with
solder and optional terminals or leads are soldered on.
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
© TT electronics plc
02.13
Ultra Low Profile
Power Resistors
WDBR Series
Terminations
The following termination options are available
Code
Option
Nominal Dimensions
9mm
Solder pad only 1
I
Flying leads
UL3134/5
40A, 600V
L
9mm
250mm
3mm
6mm
Push-on connectors
(WDBR1,2,3,5&7)
T
0.8mm
11mm
8mm
8.5mm
Notes:
1. Two options exist for solder type. The standard is SnAg (96SC) and the second is high temperature HMP alloy.
Thermal Performance
Maximum
Pulsed load at full pulse power rating 50,000 cycles (see Fig 1)
Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C.
5
ΔR%
Derating at heatsink temperatures >160°C
See Fig. 2
Fig. 1: Duty Cycle Waveform
P pk
8s
2s
% of Rated Power
1ms
1ms
Fig. 2: Temperature Derating
120
100
80
60
40
20
0
0
50
100
150
200
250
Heatsink Temperature (°C)
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
© TT electronics plc
02.13
Ultra Low Profile
Power Resistors
WDBR Series
Application Notes
A heatsink with thermal resistance ≤0.53°C/W will enable the component to operate at its continuous power rating. Thermal grease (e.g. Dow
Corning DC340) should be used and the heatsink should have a surface finish of <6.3μm with flatness of <0.05mm. The resistor should be mounted
using an appropriate bolt as listed in the table below. This should be tightened so as to bring the whole area of the steel substrate into intimate
contact with the heatsink. The unmounted part is slightly bowed so that the centre is above the edges. Inadequate tightening will leave the centre
out of contact with the heatsink, whilst over tightening can cause the edges to rise. The tightening torque required will depend on the fixings and
heatsink used, but typical figures are given for guidance. WDBR resistors will fail safe (open circuit) under overload fault conditions and still maintain
a 1kV dielectric withstand.
Bolt Size
Typical Tightening Torque (Nm)
WDBR1/2
M2
0.6
WDBR1
M3
2
WDBR2
WDBR3
M5
M5
2.5
2.5
WDBR5
M5
3.5
WDBR7
M5
4
WDBR resistors may be customised in various ways including:
Alternative shapes and dimensions up to 406mm x 406mm
Integration of temperature measurement elements
Alternative ohmic values, tolerance & TCR
Increased dielectric withstand voltage
Custom braking resistors with UL approval
For a full Applications Note for dynamic braking see http://www.welwyn-tt.com/pdf/application_notes/WDBR.pdf
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Overload Conditions
Single Overload Energy Capacity
Maximum Single Overload Power
100
10
WDBR7
WDBR5
WDBR3
WDBR2
WDBR1
WDBR1/2
1
0.1
0.01
0.1
1
10
100
W
Energy (kJ)
Power (kW)
100
WDBR5
WDBR3
WDBR2
WDBR1
WDBR7
10
WDBR1/2
1
0.1
0.01
0.01
0.1
1
10
100
Duration of Overload (s)
Duration of Overload (s)
Maximum peak current (A)
Value
(ohms)
12
15
20
22
25
47
50
100
WDBR1/2
15.2
15.2
7.6
7.6
7.6
7.6
7.6
7.6
WDBR1
21.6
21.6
21.6
8.3
8.3
8.3
8.3
8.3
150
8.3
WDBR2
20.3
20.3
7.6
7.6
7.6
7.6
7.6
7.6
7.6
WDBR3
25.4
25.4
25.4
25.4
11.4
11.4
11.4
11.4
11.4
WDBR5
25.4
25.4
25.4
25.4
25.4
10.2
10.2
10.2
10.2
WDBR7
44.5
44.5
44.5
44.5
44.5
20.3
20.3
20.3
20.3
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
© TT electronics plc
02.13
Ultra Low Profile
Power Resistors
WDBR Series
Ordering Procedure
Example: WDBR2 at 100 ohms and 10% tolerance with standard solder, flying leads and packed in a box of 84 pieces:
WDBR2–100RKLW
Type
Solder Option
96SC Standard
HT
HMP
High temperature
Value (use IEC62 code)
Tolerance (use IEC62 code)
K
10%
Termination
I
L
T
Solder pad only
Flying leads
Push-on connectors
Packing
W
WDBR1/2I
180/box
WDBR1/2T
64/box
WDBR1/2L, WDBR1L, WDBR2L, WDBR3I, WDBR3T,
WDBR5I, WDBR5T
WDBR1I, WDBR2I
WDBR1T, WDBR2T
WDBR3L, WDBR5L,
WDBR7 all terminations
Bulk
40/box
Standard
100/box
80/box
20/box
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
© TT electronics plc
02.13