Resistors
Resistors
Ultra Low Profile
Ultra Low Profile
Power Resistors
Power Resistors
WDBR Series
WDBR Series
Ultra low profile thick-film on steel
Ultra low profile thick-film on steel
500W to 7kW peak power
500W to 7kW peak power
Single fixing heatsink mountable
Single fixing heatsink mountable
Ideal for dynamic braking, inrush limit and snubber circuits
Ideal for dynamic braking, inrush limit and snubber circuits
Choice of flying lead, push-on or solder terminations
Choice of flying lead, push-on or solder terminations
Low inductance design
Low inductance design
High isolation, even after failsafe overload fusing
High isolation, even after failsafe overload fusing
RoHS compliant, non-flammable construction
RoHS compliant, non-flammable construction
All Pb-free parts comply with EU Directive 2011/65/EU (RoHS2)
All Pb-free parts comply with EU Directive 2011/65/EU amended by (EU) 2015/863 (RoHS3)
Electrical Data
Electrical Data
Resistance range ohms
Resistance range ohms
Resistance tolerance %
Resistance tolerance %
Pulse power rating
1
kW
Pulse power rating
1
kW
WDBR1/2
WDBR1/2
12, 15, 20, 22, 25,
12, 15, 20, 22, 25,
47, 50, 100
47, 50, 100
0.5
0.5
160
160
WDBR1
WDBR1
WDBR2
WDBR2
WDBR3
WDBR3
WDBR5
WDBR5
WDBR7
WDBR7
12, 15, 20, 22, 25, 47, 50, 100, 150
12, 15, 20, 22, 25, 47, 50, 100, 150
1.5
1.5
180
180
10
10
2.0
2.0
3.5
3.5
260
260
5.0
5.0
270
270
7.0
7.0
280
280
Power rating on fan-cooled heatsink
3
Power rating on fan-cooled heatsink
3
TCR ppm/°C
TCR ppm/°C
Power rating on heatsink
2
Power rating on heatsink
2
W
W
W
W
300
300
700
700
Maximum element temperature °C
Maximum element temperature °C
Ambient temperature range (heatsink) °C
Ambient temperature range (heatsink) °C
Dielectric withstand
4
V (dc/ac peak)
Dielectric withstand
4
V (dc/ac peak)
Inductance (typical) μH
Inductance (typical) μH
<3
<3
-55 to +200
-55 to +200
2500
2500
< +600
< +600
365
365
200
200
780
780
900
900
1000
1000
1490
1490
<4
<4
<5
<5
<6
<6
Notes:
Notes:
1. For details of pulse condition see Fig. 1 in Performance Data.
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.
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.
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
4. Based on 100% production test, duration 2s minimum
Physical Data
Physical Data
Dimensions in mm, weight without terminations in g
Dimensions in mm, weight without terminations in g
L ±0.1 W ±0.1 t ±0.1
ØD nom a nom b nom c nom Wt. nom
L ±0.1 W ±0.1 t ±0.1 ØD nom a nom b nom c nom Wt. nom
WDBR1/2
31.9
31.9
28.1
28.1
WDBR1/2
WDBR1
49.3
49.3
35.9
35.9
WDBR1
WDBR2
61
61
40.6
40.6
0.9
0.9
WDBR2
WDBR3
101.6
101.6
70
70
WDBR3
WDBR5
122
122
70
70
WDBR5
WDBR7
152.4 101.6
152.4 101.6
1.5
1.5
WDBR7
2.2
2.2
3.2
3.2
7.5
7.5
3.1
3.1
4.3
4.3
11.2
6.2
6.2
3.2
3.2
11.2
13.0
5.8
5.8
4.7
4.7
13.0
13.5
22.0
22.0
10.2
10.2
13.5
14.0
23.8
23.8
7.4
7.4
14.0
15.0
51.3
51.3
9.2
9.2
15.0
6.5
6.5
12.6
12.6
17.1
17.1
50.8
50.8
60.7
60.7
181.8
181.8
W
W
D
D
c
c
Fixing hole is located cen-
Fixing hole is located cen-
trally except on WDBR1/2
a
trally except on WDBR1/2
where the dimension from
where the dimension from
the edge by the terminations
the edge by the terminations
to the mounting hole centre is
b
to the mounting hole centre is
b
16.68mm.
16.68mm.
a
5.3
5.3
L
L
Substrate thickness = t
Substrate thickness = t
In addition to the central fixing
In addition to the central fixing
hole, WDBR7 has two corner
hole, WDBR7 has two corner
holes. These are present for
holes. These are present for
manufacturing purposes only
manufacturing purposes only
and should not be used as fix-
and should not be used as fix-
ing holes.
ing holes.
Construction
Construction
A high integrity dielectric layer is applied to a machined
A high integrity dielectric layer is applied to a machined
stainless steel substrate. Thick-film conductor and resistor
stainless steel substrate. Thick-film conductor and resistor
patterns are printed and fired, then protected with a high
patterns are printed and fired, then protected with a high
temperature overglaze. The termination pads are tinned with
temperature overglaze. The termination pads are tinned with
solder and optional terminals or leads are soldered on.
solder and optional terminals or leads are soldered on.
General Note
General Note
TT Electronics reserves the right to make changes in product specification without notice or liability.
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.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
IRC Welwyn
BI
BI Technologies
IRC Welwyn
Technologies
www.ttelectronics.com/resistors
http://www.ttelectronics.com/resistors
© Electronics plc
© TT TT Electronics plc
06.18
09.17
Ultra Low Profile
Power Resistors
WDBR Series
Terminations
The following termination options are available
Option
Code
PL
Nominal Dimensions (mm)
WDBR Size
PW
Pad Length, PL
Pad Width, PW
½
7.5
4.5
1, 2, 3, 5 & 7
9.0
9.0
Solder pad only
1
I
Flying leads
UL3134/5
40A, 600V
250mm
L
3mm
TW
Push-on connectors
T
TH
TT
WDBR Size
Terminal Height, TH
Terminal Width, TW
Terminal Thickness, TT
½
7.5
2.8
0.8
1, 2, 3, 5 & 7
12
6.3
0.8
Notes:
1. Two options exist for solder type. The standard is SnAg (96SC) which is Pb-free and the second (HT) is high temperature HMP alloy which is
Pb-bearing. Both are RoHS compliant, but the second relies on the RoHS exemption for high temperature solders and is targeted at specialist
high temperature applications.
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.
Derating at heatsink temperatures >160°C
ΔR%
5
See Fig. 2
Fig. 1: Duty Cycle Waveform
% of Rated Power
1ms
P pk
120
100
80
60
40
20
0
Fig. 2: Temperature Derating
1ms
2s
8s
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.
BI Technologies IRC Welwyn
www.ttelectronics.com/resistors
© TT Electronics plc
06.18
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. Sufficient thermal grease (e.g. Dow
Corning DC340) to give void-free coverage, or a 0.5mm thick compliant thermal pad (e.g. T Global TG-X) 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
WDBR1/2
WDBR1
WDBR2
WDBR3
WDBR5
WDBR7
M2
M3
M5
M5
M5
M5
Typical Tightening Torque (Nm)
0.6
2
2.5
2.5
3.5
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.ttelectronics.com/themes/ttelectronics/datasheets/resistors/literature/WDBR.pdf
·
·
·
·
·
Overload Conditions
Maximum Single Overload Power
100
Power (kW)
Single Overload Energy Capacity
100
Energy (kJ)
10
1
0.1
0.01
0.01
WDBR7
WDBR5
WDBR3
WDBR2
WDBR1
WDBR1/2
10
1
0.1
0.01
W
DB
R
7
W
DB
R
5
W
DB
R
3
W
DB
R
2
W
DBR1
W
DBR1/2
W
0.1
1
10
100
0.1
1
10
100
Duration of Overload (s)
Mounted on a 0.53°C/W heatsink with 5m/s forced air cooling, air temperature 25°C. ΔR ≤ 5%.
Duration of Overload (s)
Maximum peak current (A)
Value (ohms)
WDBR1/2
WDBR1
WDBR2
WDBR3
WDBR5
WDBR7
12
15.2
21.6
20.3
25.4
25.4
44.5
15
15.2
21.6
20.3
25.4
25.4
44.5
20
7.6
21.6
7.6
25.4
25.4
44.5
22
7.6
8.3
7.6
25.4
25.4
44.5
25
7.6
8.3
7.6
11.4
25.4
44.5
47
7.6
8.3
7.6
11.4
10.2
20.3
50
7.6
8.3
7.6
11.4
10.2
20.3
100
7.6
8.3
7.6
11.4
10.2
20.3
8.3
7.6
11.4
10.2
20.3
150
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.
BI Technologies IRC Welwyn
www.ttelectronics.com/resistors
© TT Electronics plc
06.18
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