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Transcript
SOLID STATE RELAYS
SERIAL CONVERTERS & SOLID STATE RELAYS
Start using solid
state relays today
The fundamental functions within the majority of process control systems involve
repeatedly performing a switching action. Solid state relays (SSR) offer the user
many outstanding benefits for this type of switching. Selection and application
is easy and here are a few simple guidelines and suggestions to help you make
the most of this technology.
Amplicon Serial Comms
Why choose Amplicon for serial communications?
Amplicon’s broad range of serial communication products serves industrial markets as well as IT applications throughout the world. As
a manufacturer we have attained a high level of expertise resulting in outstanding product quality and first rate technical knowledge.
What is a ‘Solid State Relay’?
A ‘Solid State Relay’ is a switching device
which uses transistor technology instead
of mechanical contacts to do the switching
function. This switching is performed by
a Triac or SCR (Silicon Control Rectifier)
dependant on the load type. Both these
switching devices are members of the
Thyristor family, and input to output isolation
is achieved by the use of an optocoupler.
Typical SSR Internal Construction
Advantages of solid-state v
electromechanical relays
90-280 Vac. The control voltage is considered
similar to a relay coil voltage.
Advantages:
Long life and high reliability, more
than 109 operations, reduced
maintenance costs
• No contact arcing, low Electromagnet
Interference (EMI) and high surge capability
• High resistance to shock and vibration
• Fast switching and low coupling
capacitance
• Logic compatibility and no
electromechanical noise
Disadvantages:
• Higher cost than equivalent
electromechanical relay
• Higher heat dissipation requires heat sink
Heating Applications
Selecting the correct SSR
for your application
Two output types exist within AC switching
SSRs. The first is commonly referred to as
‘Zero Voltage’ or ‘Zero Crossing’ turn-on.
This type only starts to conduct once the
AC line voltage has passed through the zero
volt point. The second type is referred to as
‘random’ or ‘instantaneous’ turn on. This type
begins to conduct as soon as the control
voltage is applied regardless of the AC line
voltage. A choice of control voltages are
available; low voltage DC control – typically
3-32Vdc, or high voltage AC control – typically
14 AUTOMATION APRIL 2008
Heating applications have repeated
frequent load cycling as the elements are
turned on and off to maintain the required
temperature. Heating elements are
predominately resistive, so surge currents at
switch-on are low. This makes Zero Voltage
turn on SSRs ideal for heating applications.
Choosing the suitable solid-state relay is
easy to do if you consider the following:
• Full Load current of the elements
• Line voltage being switched
• Available heat sink - oversize where
possible, or select a device with integral
heat sink
• Ambient temperature - in heating
applications elevated temperatures are
common and you may need to de-rate
the SSR
Therefore, to maximize the life expectancy
of the SSR, the selected device will have a
continuous rating of at least 2x the full-load
current, Zero Voltage turn-on and a voltage
rating higher than the supply voltage.
AC Motor and Coil
Control Applications
Because of the inductive nature of AC
Typical ‘Hockey Puck’ type SSR
motors, and solenoid coils, high surge
currents occur at switch-on. This makes
random or instantaneous turn on SSRs
the most suitable type. When selecting a
suitable SSR for these applications you must
consider the following:
• Full Load current of the motor or coil
• Line voltage being switched
• Starting duration and frequency
- repeated cycles will increase thermal
stress on the SSR requiring extra heat
sinking or overrating
• Ambient temperature and available
heat sinking
Due to the high current during start-up the
SSR must be over rated, compared to the
full load motor or coil current.
For motors, external over current protection
is always advisable to protect both the motor
and the solid state relay. This could take the
form of a motor protection circuit breaker
or thermal overload. Voltage selection is
important as back EMF generated during
motor wind-down or turn-off of a large coil
can be x1.5 – x2.5 line voltage. To ensure
the maximum operational life the selected
SSR, it should have a current rating of at
least 3x the full load current, random turnon, and an over-voltage rating of more than
twice the line voltage. n
Latest technologies from the leading automation brands
RS232 to RS422/485 converters
Serial to Ethernet converters
Amplicon have manufactured RS232 to
RS485 converters for over 20 years.
Serial to Ethernet converters offer a
cost-effective solution for the integration
of legacy serial equipment (RS232, RS422
or RS485 devices) into modern
Ethernet networks.
•
Convert RS232 to RS485 and vice-versa
•
•
•
RS232 links up to 1.2km if used in pairs
Optical isolation available for data integrity
Automatic turnaround for connecting to 2-wire RS485 networks
•
•
•
•
Transmit serial data across a LAN, WAN or even the internet
Use existing networks instead of installing new cable
Centralised control of remote devices
Easy to configure with 5 year warranty as standard
221-402
Model 232i-9
IN-LINE 1 PORT RS232 ISOLATOR
£69.00
221-395
485H-F9
RS232 TO RS422/485 CONVERTER
£55.00
221-503
485F9i
RS232 TO RS422/485. OPTICAL ISOLATION
£75.00
221-367
MA485F9
RS232 TO RS422/485. AUTOMATIC TURNAROUND
£65.00
221-519
SE5001-S2
1 PORT RS232 TO ETHERNET CONVERTER
£110.00
221-373
USB-232U
1 PORT UNIVERSAL USB TO RS232 ADAPTER
£89.00
221-351
SE5001-S5
1 PORT RS422/485 TO ETHERNET CONVERTER
£125.00
221-389
USB-485Ui
1 PORT USB TO RS422/485 ADAPTER
£119.00
221-200
SW5001
1 PORT RS232/422/485 TO WIRELESS LAN
£199.00
Amplicon IT and instrumentation for industry
THREE PHASE SSR
NEW GN SERIES
SMART MODULE
NEW GN SERIES SSR
WITH HEATSINK
A new retro-fittable module which can be
mounted on top of a Crouzet GN series
or any ‘hockey puck’ solid state relay and
provides visual and electrical feedback that
an error or failure has occurred.
A puck style SSR with pre-fitted finned
heatsink and DIN rail mount fitting.
Heaksink allows SSR to be used up to its
full rating within ambient temperatures up
to 40ºC.
• INPUT and ERROR LED indicaton
• Sense line voltage - 24-660Vac
• 4-32Vdc transistor alarm output
• Mounts on any standard puck type SSR
• 4-32Vdc control input
• Zero Volt switching
• EMC compliant
• LED input status indication
The D53TP series provide three phase
switching in a compact puck style body
using SCR outputs for maximum reliability,
with a variety of load types such as motors,
heating elements and transformers.
• LED status indication
• Line voltage – 48-530Vac
• Screw terminals
• Matching heatsink available
– nominally 45mm x 60mm
509-1225
Smart module
£24.27
rswww.com/automation 08457 201201
499-0301
7A 24-280Vac SSR
£32.96
499-0317
9A 24-280Vac SSR
£35.02
499-0323
13A 24-280Vac SSR
£37.08
499-0373
15A 24-280Vac SSR
£39.18
499-0418
25A 24-280Vac SSR
£42.27
499-0424
30A 24-280Vac SSR
£43.30
184-5983
25A 3-32Vdc control
£62.85
184-5999
50A 3-32Vdc control
£70.11
218-1915
25A 90-280Vac control
£71.14
218-1921
50A 90-280Vac control
£82.99
613-8094
MS3 DIN rail mount
heatsink
£26.73
AUTOMATION APRIL 2008 15