User Manual

4
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1. Choose insulation type
Pick from the available insulation types. When selecting
insulation consider temperature range, maximum
resistance density and maximum heater size. Insulation
options are available on page 7.
2. Choose installation option
Proper installation is crucial for optimal heater
performance. Determine the best method to install
flexible heaters in your application so you can achieve
desired results in your thermal system. Minco installation
options are available on page 8.
3. Calculate required wattage
The heater you select must produce enough power to
(1) warm the heated object to control temperature in
the desired time and (2) maintain that temperature. The
specific heat formula on page 15 gives an estimate for
warm-up, assuming all heat enters the object and none is
lost. Add at least 20% to account for unknown losses.
Heat loss factors include conduction, convection, and
radiation. A more accurate wattage estimate will take
these into account. For a general discussion of heat
loss, download Minco White Paper “Estimating Power
Requirements for Etched-Foil Heaters.” Also helpful is
Thermal Calc, an online tool to assist with calculations.
Both are available at www.minco.com.
4. Select a Minco stock or standard heater
Select from the hundreds of available heater sizes in this
guide that will best fit your application. Multiple resistance
options will allow you to carefully manage your heat
output.
5. Test and prototype
The best way to make a final determination of heat
requirements is by experimentation. See page 18 for tips,
or download Minco’s white paper entitled “Prototyping
Techniques for Etched-Foil Heaters,” available at www.
minco.com.
Heater selection examples
Desired temperature
60°C 100°C 150°C
Power required
300 W at 115 V 500 W at 240 V 2500 W at 480 V
Heater size
3” × 6” (76.2 x 152.4 mm) 2” × 10” (50.8 x 254 mm) 9” (228.6 mm) diameter
Ideal resistance
115²/300 = 44.1 W 240²/500 = 115 W 480²/2500 = 92.2 W
Mounting method
BM3 shrink band #6 RTV cement Factory vulcanized Clamped
Insulation
Polyimide Silicone Rubber Mica
Model chosen
HK5468 R46.1 L12 A HR5430 R96.8 L12 A HM6810 R83.4 L12 T2
Eective area
15.74 in² (101.5 cm²) 18.20 in² (117.4 cm²) 58.5 in² (377.4 cm²)
Actual power
115²/46.1 = 287 W 240²/96.8 = 595 W 480²/83.4 = 2762 W
Watt density
287/15.74 = 18 W/in² (2.79
W/cm²)
595/18.20 = 33 W/in² (5.12 W/cm²) 2762/58.5 = 47 W/in² (7.29 W/
cm²)
Max. watt density
36 W/in² (5.58 W/cm²) at 60°C 19 W/in² (2.95 W/
cm²) at 100°C
36 W/in² (5.58 W/
cm²) at 100°C
54 W/in² (8.37 W/cm²) at 150°C
Wattage density OK?
Yes (18 < 36) No! (33 > 19) Yes (33 < 36) Yes (47 < 54)
Selecting a Minco Heater
Follow these steps to select your heater
A Thermofoil heater has a specific resistance. Its power
output, in watts, depends on supply voltage (P=E²/R).
R
Ohms (W)
P
Watts (W)
I
Amps (A)
E
Volts (V)
I
E
P
E
2
2
I
P
IE
RI
2
R
E
2
R
P
E
P
R
E
PR
I
P
RI
Ohm’s Law