Literally a solid
state relay is an electronic switching device. In this relay a small
regulating signal controls a greater load current or voltage. It comprises of a
sensor which gives feed back to an appropriate control signal, a device which
gives power to the load circuit and this device is known as solid state
electronic switching device. Such relays are made with a purpose to switch AC
or DC to the load. More interestingly this device has no moving part.
This relay is made on satisfying
a number of parameters. The parameters include input voltage required for
initial activation, current, output voltage and either AC or DC current,
voltage drop and others. These are the parameters required to safeguard the
interest of user firms. The solid state
relay has numerous benefits over mechanical relays. There are huge
operational benefits. These relays are based on a single MOSFET or number of
MOSFETs in a parallel. These MOSFETs have an inherent substrate diode which
conducts in reverse direction so it is clear a single MOSFET cannot block
current in both directions therefore required number of MOSFETs are employed.
On the operational parameter there is lesser concern of wear and tear as is in
the case of mechanical relays. It has following winning points over mechanical
relays.
1) SSRs
being faster than electromechanical relays, take less switching time.
2) SSRs
are incredible life time as there are no dynamic parts to wear.
3) Output
resistance is constant despite being used number of times.
4) Lesser
noise while operating
5) Less
sensitive to environmental concerns.
6) No
sparking.
Etc.
These are the
benefits which make it preferable over mechanical relays by the firms involved
in the business which uses these relays in an extensive manner. All these
advantages counts and are really important when the working involves the
switching of highly capacitive loads and this is also counted as a major
advantage over electromechanical switching or relay.
On the application part if we talk more deeply then it is
used for heater control, for three phase motors, socket/plug in type. In heater
control, these relays enable high precision, high frequency temperature control
for ovens, molding machines, sintering ovens. For three phase motors it provide
smooth starting and stopping functions to avoid sudden motor operation and thus
reduce mechanical stress. Therefore it is clear that these relays are required
for smoother movement.
The world of electronics technology is in the
great demand of SSRs for their smoother industrial operations. SSRs or solid
state relays are being manufactured in every major industrial country. It means
the technical advancement in modern world has greatly to do with these relays
because being conducive for the operation these are raking more profits to the
electronic and electrical industries. In our country too, various industrial
houses are associated with the manufacturing and marketing division of solid state relays for its stress
tolerating and good working 