Q1. List and briefly describe the 2 main issues with Power Supply Units (PSUs). Q2. Briefly describe any 4 applications for different type of screened cables. Q3. What are 2 main principles of cable...

Q1. List and
iefly describe the 2 main issues with Power Supply Units (PSUs).
Ans:
1. Power switching components, or MOSFETS, which take the
unt force of operation of the
power supply, can sometimes cause failure if the heat sinking is inadequate, or if the drain
overvoltage, drain overcu
ent, gate overvoltage, or the internal antiparallel diode is
overstressed.
2. Control ICs often have an unusual region of operation and, if misunderstood or misapplied, can
lead to failure. This includes inco
ect clock operation or improper PCB layout, which will make
the control IC susceptible to noise or oscillation. All controller ICs have their own unique
ehavior and need to be well-understood in the application, including the work-arounds and
“undocumented features” for the intended application.
To avoid failures with commercial control ICs, start-up conditions must be understood. Cu
ent
limiting, soft-start modes, proper gate drive, spacing, and measuring the control loops — all must be
done to ensure stable operation over all conditions.
Q2. Briefly describe any 4 applications for different type of screened cables.
Ans: shielding in cables acts as a ba
ier that protects the cable from external threats, such as electrical interference (EMI). It
also prevents cable signals from interfering with su
ounding cables and equipment.
1. F/UTP (FTP)
An overall foil shield (F) with unscreened twisted pairs (UTP). This cable is very much like common UTP cables, with the addition
of foil underneath the main cable jacket. Another common name for this cable is FTP. F/UTP cables are common in 10GBaseT
applications.
2. S/UTP
An overall
aid screen (S) with unscreened twisted pairs (UTP). These are occasionally refe
ed to as an STP cable, but beware:
There are other shielded cables among this list that may also claim this term. To be sure, always check to see whether your
cable will have any kind of overall ba
ier, and whether the individual pairs have their own shield.
3. SF/UTP
Both an overall
aid screen (S) and foil shield (F) with unscreened twisted pairs (UTP). This cable is also occasionally refe
ed to
as an STP cable. Cables with an overall
aided screen are very effective at protecting EMI from entering or exiting the cable.
4. S/FTP
An overall
aid screen (S) with foil screened twisted pairs (FTP). The “shield” underneath the jacket is a
aid,
and each individual pair is su
ounded by its own foil ba
ier. The purpose of the additional foil on individual pairs is to limit the
amount of crosstalk between them.
Q3. What are 2 main principles of cable routing?
Ans: The two main principles of cable routings are:
 The cable between two items of equipments must always follows the same route,
 There should be single interconnection panel for each item of equipment
Where you need several routes and/or connection panels, each should have its own PEC and higher
PEC earth cu
ents should be expected
*Stacking cable trays along a route
Because of the minimum segregation distances required between cables classes. It is generally
impossible to run cables of all four classes along one cable tray. This is overcome by running a “stack
of cable trays”.
Always route send and return conductors very close together Every DC or AC electrical power or signal,
whether analogue, digital or radio-frequency (RF), always has a ‘return’ cu
ent that is equal to the
‘send’ cu
ent. The send and return cu
ents always flow in a loop, from their sources to their loads and
ack again to their sources. To help achieve EMC this loop area should be as small as possible.
Q4. List any 2 advantages of using screened connectors.
Ans: The advantage of using screened connectors:
– The connector is fully screened making it unaffected by adverse environmental conditions.
– The two Faraday cages featured within the connector eliminate the need for separately installed stress control
and taping of components.
– Tee connectors can ‘piggybacked’, allowing more than one cable to be attached to a single bushing.
– Each unit is factory tested for partial discharge and power frequency withstand (dependant on manufacturer).
– Can be installed both indoor and outdoor environments.
– Connectors can be utilized to joint cables together, using the appropriate mating part.
Q5. List any 3 filter thumb rules for various available conditions for unwanted signals?
Ans: In circuit theory, a filter is an electrical...