Interested to Buy Any Domain ? << Click Here >> for more details...
What is the difference between Relay and Contactor
- 35 Answers
- 159467 Views
- Siemens, I also Faced
- E-Mail Answers
Answer Posted / wleob
1) All of the previous answers are mostly correct.
2) In general, a relay and a contactor have at least the
same two basic parts:
a. A coil that makes the contacts close or open. The coil,
whether energized by AC or DC always uses much less current
(amps) to operate than the current, AC or DC that the
contacts can carry. Coil ratings can be from 12 VDC to 600
VAC, for example.
b. Contacts, rated DC or AC that open or close a circuit to
a load (resistance or inductance) which demands more current
(amps) than the coil does. Relay contacts are usually
applied to lower amperage circuits and Contactor / Motor
Starter contacts usually carry higher voltages and amperage.
3) AC and DC coils are built differently. AC coils have
steel plates to break up the eddy currents inherent in AC.
As AC goes "through zero" 60 times per second, no
discharging diode is required. The rating on the coil will
state whether it is for 60 Hertz (cycles per second) , 50
Hertz (CPS) or 60/50 Hertz, meaning it can be used in the
USA or Canada. DC coils usually have a diode and/or a
capacitor for the inherent discharge of the coil when the
voltage is removed. The current going through the coil must
be discharged as the field in the DC coil collapses.
4) AC contacts in low power applications don't require any
special arc chutes as AC, again goes through zero 60 times
per second (50 times per second in Canada). DC contacts in
low power applications do not require arc chutes. However,
as the current being carried gets larger and if the load is
not pure resistance, the discharge power must be dissipated
or "blown out" in an arc chute.
5) In summary, relays are usually applied to control
circuits and in lower power applications while contactors
usually imply that they are controlling larger loads with
higher current (amp) requirements. Industrial relays
typically can carry 5, 10 or 20 amps as do the relays in
your cars fuse box for your headlights, blower motor, or
your trailers electric brakes. However, though called a
starter "relay" it is contactor that will carry at least 100
amps to run your starter motor. AC Motor "starters"
/contactors typically have 120 VAC coils or 460 VAC coils
and can run motors that require from 5 amps to 100s of amps.
Hope this helped,
WLeoB
BSEE '71
Canton, MI
| Is This Answer Correct ? | 7 Yes | 2 No |
Post New Answer View All Answers
Why you are switching off arc protection mcb when you are taking shutdown for lv board.
what is the difference between active power and reactive power and apparant power in practical as well as theoritical
what causes contact chatter when there is no demand on the air conditioning unit?
Mention the disadvantages of low power factor?
what is static frequency converter?what is the function...of sfc...?
Why front mounted CT polarities are always towards breaker?
1.what is the difference between transformer differential and busbar differential.2)why we are using 2 slope for trafo diif and 1 slope for busbar diff.3)what is the purpose of metrosil and stabilizing resistor in high impedance relay circuit.4)how metrosil reduce the peak volage.5)what is the funtion of stabilizing resistor
Why the arms of delta in a delta-wye power transmission system are kept constant??
What are the Formula of computing Back up Time of 500kVA UPS with 4 Battery Banks, each bank composed of 43 pcs of Batteries 12V150Ah. How to compute the Back up Time of UPS? We have also 3X500kVA UPS running in Parallel same composition as I write above.
what is difference between isolation and ultra isolation transformer?, what is the method of testing ?
what is the differance between HT motors And LT MOTORS.
What are the advantages of thermal power plant?
why we used dc supply for field in dg set
What is CCM in Electrical ? where can we use this material?
What is critical disruptive voltage?
