HK1 Crydom Co., HK1 Datasheet - Page 4

• Manufacturer Part Number: HK1
• Description: SSR MOUNTING HARDWARE KIT
• Manufacturer: Crydom Co.

Specifications of HK1

• Accessory Type: Mounting Hardware
• Associated Relay Series: Crydom Heatsinks Except for HS501DR
• Mounting Style: Panel
• Termination Style: Screw
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: HS Series Heatsinks
• For Use With: CC1703 - HEATSINK SSR 0.5DEG C/W PNL MNTCC1702 - HEATSINK SSR 0.7DEG C/W PNL MNTCC1701 - HEATSINK SSR 1.0DEG C/W PNL MNTCC1700 - HEATSINK SSR 1.2DEG C/W PNL MNTCC1699 - HEATSINK SSR 1.5DEG C/W PNL MNTCC1698 - HEATSINK SSR 1.7DEG C/W PNL MNTCC1697 - HEATSINK SSR 2.0DEG C/W PNL MNTCC1696 - HEATSINK SSR 2.0DEG C/W PNL MNTCC1695 - HEATSINK SSR 2.5DEG C/W PNL MNTCC1694 - HEATSINK SSR 2.7DEG C/W PNL MNTCC1693 - HEATSINK SSR 3.0DEG C/W PNL MNTCC1692 - HEATSINK SSR 3.5DEG C/W PNL MNTHS103DR - HEATSINK SSR 1.0DEG C/W DIN MNTCC1790 - HEATSINK SSR 1.2DEG C/W DIN MNTHS151DR - HEATSINK SSR 1.5DEG C/W DIN MNTCC1791 - HEATSINK SSR 2.0DEG C/W DIN MNTCC1792 - HEATSINK SSR 2.0DEG C/W DIN MNTHS271DR - HEATSINK SSR 2.7DEG C/W DIN MNTHS301DR - HEATSINK SSR 3.0DEG C/W DIN MNTCC1793 - HEATSINK SSR 3.5DEG C/W DIN MNT
• Color: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: CC1706

4
Heat Sink Selection
reliability of Solid State Relays because they provide a means to dissipate
the power that is normally developed internally in the SSR into the
surrounding ambient air and maintain a safe operating temperature.
All SSRs in their conduction state create thermal energy in the output
semiconductor at the rate of approximately 1 to 1.5 watts per ampere of load
current for AC output SSRs, and 0.2 to 1.5 watts per ampere of load current
for DC output SSRs depending upon their design. This power dissipation
raises the Solid State Relay’s operating temperature above the surrounding
ambient.
Solid State Relays can operate reliably without heat sinks up to
approximately 5 amps of load current depending upon model, duty cycle
and ambient temperature. Free air ratings of traditional panel mount SSRs
may be as high as 8 to 10 amps, but this rating relies on the SSRs exposed
metal base plate acting as a heat sink, meaning that it must be exposed to
ambient air.
aluminum. Not only is aluminum’s thermal conductivity high, its cost is
relatively low. Although other materials such as steel may provide a limited
measure of heat sinking, thermal conductivity of these materials are
relatively low compared to aluminum and therefore far less effective as a
effectiveness of most materials and except anodizing, should be avoided.
watt (°C/W) (thermal impedance is the inverse of thermal conductivity).
Thermal impedance represents the resistance to the transfer of thermal
energy, therefore lower numerical thermal impedance ratings mean more
efficient heat transfer.
Thermal Impedance ratings of
convection air flow. To achieve this performance, the
oriented such that air flow over its finned surface is maximized. Generally
this means the fins should be orientated vertically.
Significant improvement in
providing forced air flow over the
relatively small volumes of air can reduce the Heat Sink’s thermal
impedance substantially, thereby improving its efficiency and consequently
the SSRs reliability.
Crydom offers technical assistance selecting a heat sink for any given SSR
application through its Applications Engineering Department and on its web
site. Available “White Papers” and a selection “tool” to calculate a heat sink
rating based upon load current and ambient temperature are available at
The basic structure of a Solid State Relay includes an internal power
semiconductor mounted to an electrical insulator which in turn is mounted
to the Solid State Relay’s base plate. To form an assembly, the SSR with an
accompanying thermal interface material placed on its base plate is then
torque mounted to the
The thermal model representing the above configuration includes the
following elements:
State Relay operation
Relay application
given Solid State Relay application
Why Heat Sinks are required for Reliable Solid
Selecting a Heat Sink for a given Solid State
How to calculate and select a Heat Sink for a
performance is rated by thermal impedance, measured in °C per
.
are required to insure the proper operation and long term
are made of high thermal conductive material such as
Coatings also tend to diminish the thermal dissipation
Questions?
.
.
Call or e-mail
performance can be achieved by
surface area. Fans delivering
are based upon natural
Europe
Americas
[phone]
must be
[phone]
T
T
T
T
T
J
B
HS2
HS1
A
To determine the minimum Heat Sink rating (R
application, the SSRs internal power dissipation must first be calculated.
The power developed in the SSR will be the product of the actual load
current in amps times the SSRs specified on state voltage drop at that
current ( P
forward voltage drop' in their data sheets. Typical voltage drops are often
much lower.
For this example, assume that a 25 amp AC output SSR is selected to switch
an AC load current of 18 amps with forward voltage drop specified to be 1.25
volts. Therefore the power generated in the SSR is 18 amps times 1.25 volts
= 22.5 watts.
Next, determine the Solid State Relay’s specified thermal impedance and
allowed maximum internal temperature (if the max internal temperature is
not specified by the manufacturer, assume 125 °C as this is a common value
for many AC power semiconductors). For this example, assume R
°C/W and T
The next step is to determine the maximum operating ambient temperature
(T
ambient value should be the ambient air temperature of the local
environment such as the interior of a control cabinet where the SSR and
Heat Sink are to be mounted. In this example, assume T
Finally, the thermal impedance of the interface material (R
determined. These materials will vary from 0.02 to 0.1 °C per watt
depending upon the type and thickness selected. For this example, assume
that the thermal impedance of the selected interface material R
°C/W.
The first calculation is to determine the temperature span (∆t) that the
SSRs power must be dissipated into in order to maintain its proper
operation. This will be the difference between the SSRs maximum allowed
internal temperature and the local ambient temperature. ∆t = T
In this example the result would be: ∆t = 125 – 55 = 70 °C.
The maximum allowed temperature rise noted above, ∆t, must then be less
than or equal to the combined sum of temperature rises across the three
impedances times the power being developed in the SSR. ∆t < (R
+ R
Therefore the Heat Sink thermal impedance is R
or 70/22.5 – 0.35, equaling 2.76 °C/W.
Therefore in this example, a 2.75 °C/W or larger (lower numerical value)
Heat Sink should be used with the Solid State Relay in the application as
described above.
A
B
C
D
A
) in °C that the SSR will be expected to operate in its application. The
Θ hs
The selected SSR with specified thermal impedance (R
voltage drop (V
(T
The thermal interface material placed between the SSR and the
The calculated minimum
required for proper SSR operation.
The operating environment’s max ambient air temperature in °C (T
j
).
) times P
and its specified thermal impedance (R
A
d
j
[e-mail]
[e-mail]
Solid State Relay - Heat Sink Assembly Thermal Model
R
= I
of 125 °C.
d
θSSR
. For this example it would be 70 < (0.3 + 0.05 + R
f
x V
f
), and maximum allowed internal operating temperature
B
f
). Note: Manufacturers generally specify 'maximum
R
θTP
C
R
θHS
D
thermal impedance rating (R
T
A
Θ hs
Θ hs
Θ tp
) required for a particular
).
< (∆t /P
A
B
C
D
Panel Mount SSR
Thermal Interface Material
Heat Sink
Ambient Air
A
of 55 °C.
d
) – (R
Θ ssr
Θ tp
) must be
Θ tp
j
Θ hs
), forward
Θ ssr
max – T
Θ ssr
Θ ssr
) x 22.5.
is 0.05
+ R
of 0.3
+ R
A
).
Θ hs
Θ tp
Θ tp
A
)
)
.