2. SURGE
Power
Surge or transient voltage, is an increase in
voltage significantly above the designated level in a flow
of electricity.
These transients attack the equipment through power
input lines, signal input and output lines, data lines and
any other wire coming into or going out of electronic
devices.
3. It
is the low intensity surge
twice the nominal line
voltage and relatively long
in duration ,about one
millisecond.
Damaging surges typically
are shorter, measured in
tens of nanoseconds, and
much higher intensity, ten
to twenty times larger
than normal voltage.
5. Surge Suppressor
Surge suppressor is a device inserted in alternating current(AC)
utility lines which typically used to protect electronic equipment from
damage or destruction cause by transient voltage and surge current.
A typical surge suppressor is a small box with several utility outlets, a
power switch and a 3wire cord for plugging into a wall outlets.
6. .Need for surge suppressor
The electronic equipment containing
transistor ,integrated circuit are vulnerable to
damage by transients over voltages on AC
supply mains.
In the absence of surge suppressor , the
transient over voltage may have as high as 6kv
.these pulses are of short duration and
measured in microsecond ,can destroy
transistor ,integrated circuit and sensitive
component.
7. The Process of Protection
A
standard surge protection passes the
electrical current along from the outlet to a
number of electrical and electronic devices
plugged into the power strip. If the voltage
from the outlet rises above the accepted
level- the surge protector diverts the extra
electricity into the outlet’s grounding wire.
In the most common type of surge protector,
a component called a metal oxide varistor, or
MOV, diverts the extra voltage,
8. MOV forms a connection
between hot power line
grounding line
MOV has three parts: a piece
of metal oxide material in the
middle, joined to the power
and grounding line and two
semiconductors
.
9. Working of MOV
These semiconductors have a variable resistance that is dependent
on voltage. When voltage is below a certain level, the electrons in the
semiconductors flow in such a way as to create a very high
resitance.When the voltage exceeds that level, the electrons behave
differently creating a much low resistance. When the voltage is correct, an
MOV does nothing. When voltage is too high an MOV can conduct a lot of
current to eliminate the extra voltage.
As soon as current is diverted into the MOV and to ground, the
voltage in the hot line returns to a normal level, so the MOV’s resistance
shoots of again. In this way, the MOV only diverts the surge current while
allowing the standard current to continue powering the machines
connected to the surge protector.
10. Surge connection
A
series connected surge suppressor
It act as a roadblock. The surge must travel through the suppressor
on its way to our equipment. The suppressor removes or
smoothes out the surge on its way. So no voltage are left to harm
our equipment.
A
parallel connected surge suppressor
It is connected in parallel to the computer across the leads of the
power line just as the computer. The surge suppressor works by
shorting out the surge, routing its high voltage direct from hot to
neutral , before the surge voltage on the power line rises to a
point at which can damage our computer.
11. Installation Location
A series connected surge suppressor must be located between the
source and our computer .
A parallel connected surge suppressor could be located any where
in an electrical circuit as long as it can provide a lower resistance
path to ground than the circuit of our computer’s power supply.
Most common surge suppressor takes the form of outlet strips
function ay the device level or at the point of use as described in
industry. They are meant to protect only a single device or few
devices.
Whole premises or whole house surge is install in our fuse box or
breaker panel. It has the advantage that they protect everything in
our office and home against external surges.
13. Voltage Signal Surge
Protectors
Description:
These are a line of transient
surge protection devices used
in one way unipolar (bipolar)
systems.
It requires a remotely located
transducer. This result in
transmission wire being
connected between the
transducer and data acquisition
system, acting as a signal
carrier as well as the transient
voltage and surge current
carrier.
14. Working
It has a line side which is connected to the transmission wire and a protected side
which is connected to the sensitive equipment.
It provides three stage of protection for signal path.
Stage 1:
The input of the module includes an inductor which slows
down rise time of the transient and provides an impedance mismatch resulting in
some of the transient energy being reflected back down the supply lines.
Stage 2:
In this stage tight voltage clamping is provided.
Stage 3:
In this stage protection is provided by MOV which suppress large surge current and
clamp the larger spikes. All destructive voltages and currents are absorbed into an earth
connection.
15. Features
Tight
clamping voltage
High surge current handling capability
Low series resistance
Very high resistance during normal operation
100% redundancy
16. AC Surge Suppressor
Description:
These are a line of transient
surge protection devices
used in single phase AC
supply voltage
application. These devices
are design to provide
protection for electronic
equipment requiring
connection to an AC
supply.
17. Working
It has a line side which is connected to the AC supply LIVE and NEUTRAL and a
protected side which is connected to the sensitive equipment.
It provides three stage of protection for signal path.
Stage 1:
The input of the module includes an inductor which slows down rise time
of the transient and provides an impedance mismatch resulting in some of the
transient energy being reflected back down the supply lines.
Stage 2:
In this stage protection is provided by MOV and a thermal fuse. The
MOV suppresses large surge current and clamps voltage spikes that just above
the maximum supply tolerance level. Once the MOV reaches the end of its
useful life, the thermal fuse blow, the MOV will removed from the circuit, and
the green LED will be extinguished. This MOV accounts for appx 12% of surge
protectors total protection capacity
Stage 3:
In this stage protection is provides the remaining 88% of protection
capacity in the form of an arrays of MOVs.The LIVE and NEUTRAL are
protected individually as well as differential mode.
18. Features
Tight
clamping voltage
High surge current handling capability
Very high resistance during normal
operation
LED indicator ensures continued
protection
100% redundancy
19. Surge Suppressor Rating
Peak surge current
This represent the maximum transient current that the suppressor
can handle during a surge.
Joule rating
It is a measurement of energy absorption capability of the surge
processor
Response time
It tells at what time delay they respond to the power surge.
Clamping voltage
It tells what voltage will cause the MOVs to conduct electricity to
the ground line.
20. Limitation
Continues conduction of the
varistor make it hot. At somewhere
lower power dissipation in the
varistor, the varistor may become
hot enough to melt plastics in the
vicinity of the varistor.In some cases
flammable plastic might be ignited by
hot varistor.
21. Conclusion
Surge
suppressors should be used as a matter
of habit with all semiconductor based
electronic and computer hardware including
peripherals such as printers monitors,
external disk drivers and others. But it can’t
be relied upon to provide protection against
lightning induced transients. So the safest
procedure to ensure that all susceptible
hardware is to unplug the suppressor main
power cord during lightning.
