Switch Contact Materials, Functions, & Types

Contacts are the point where a switch (or relay) throw makes or breaks a circuit. Switch contacts are always found in pairs. The contact that moves with the switch actuator is the movable contact or lever; the contact that is fixed is called the stationary contact.


Contact Materials

Contacts are subject to heat, arcing, corrosion, welding, pitting, and contaminating materials. The most appropriate contact material will differ depending on load type. Carling offers a variety of contact materials ranging from gold for dry circuits (low current circuits that do not produce an arc) to various silver alloys for high inrush loads. The most commonly used contact material is silver. Silver has low resistance and is one of the best conductors for electricity.


Contact Functions

Contact functions can be described as make-before-break or break-before-make.

Make-before-break switches are those that will complete a new circuit before breaking an old one. With this type of function, the next contact is made or closed before the previous contact is broken or opened. This can also be referred to as a shorting type switch. A typical application example for use of this type of function would be a computer switching from AC to a DC backup system.

Break-before-make switches are those that will only complete one circuit at a time, leaving an interval of time between the time one circuit opens and the next circuit closes. This can also be referred to as a non-shorting type switch. In general, all Carling Technologies’ switches are break-before-make switches.

Single Break or Double Break

Single break / single make contacts are those that open and close a circuit at only one place.

Single Break

Single Break

Double break/double make contacts are those that open at two separate places on a circuit. Double break contacts dissipate heat more readily, providing longer switch life and enabling the switch to handle higher voltages.

Double Break

Double Break

Slow Break or Quick Break

When contacts separate, arcing or sparking can occur between the two contacts. Arcing can burn up the contacts and reduce the useful life of the switch. The arc resulting from a DC voltage will be greater and will last longer then the arc from an AC voltage, because DC current has a constant value in relation to ground and zero. Because of constant electrical flow, DC switches should ideally be quick break. Quick break circuits typically require less than 5 milliseconds to make or break. Carling AC/DC toggles and pushbutton switches utilize a quick break design.

AC current has a value that is always rising or falling in relation to zero. Whenever AC current reaches zero (120 times per second) it cannot create a spark. Because of this, AC switches can be either slow or quick break. Slow break circuits typically require 8-12 milliseconds to make or break. Most Carling AC rated switches utilize a slow break design.


Contact Types

Wiping action contacts are “self-cleaning” contacts that wipe or slide against each other when opening or closing a circuit. This wiping action helps prohibit the build-up of any non-conductive deposits on the contacts themselves. Wiping contacts are typically used in AC applications, but are also suitable for low voltage DC applications.

Wiping action contacts can include some limitations on current, voltage, and lifecycle, and they require some form of lubricant, such as grease, to facilitate movement. With repeated arcing, the level of contaminants can increase and be captured by the lubricant around the contact area. This could eventually affect the operation of the switch.

Carling switch series which offer wiping contacts include R , LR , 610/620, 611/621, T, LTA, TG, LTG, TTG, TLG, C, D, DK/EK, 641, 700, and 800.
Carling Wiping Rocker Switches
Carling Wiping Toggle Switches
Carling Wiping Pushbutton Switches
Carling Wiping Selector Switches
Carling Wiping Circuit Breakers

Butt action contacts press “head-on” against each other when closing a circuit. They are much more versatile than other types of contacts, having the ability to handle multi-purpose loads from dry circuits up to 20 amps, and the ability to modify contact material, thickness or alloying agents. Butt action contacts are suitable for both AC and DC type switches.

Carling switch series which offer butt action contacts include: Contura II & III, Contura IV & V, Contura X & XI, Contura XII, J Series, L Series, RSC, RGS, LRGS, 611/621, 622/632, 651/652, TIL, TIG, TIH, TII, LTIL, LTIG, LTIH, LS, LT, F, G, H, I, MAAOA/215, P, PP, 170/72, P26, P27, 16-3P, and R135.
Carling Butt Action Rocker Switches
Carling Butt Action Toggle Switches
Carling Butt Action Pushbutton Switches
Carling Butt Action Selector Switches
Carling Butt Action Circuit Breakers

Roller contacts are a different style of butt action with an over-center, non-teasable mechanism. They are typically used on AC/DC switches that have size constraints. They are an example of a double break style contact where both the line and the load are broken simultaneously.

Carling switch series which offer roller action contacts include 110/216 and 110/316-P.
Carling Roller Action Pushbutton Switches

Knife-blade contacts are a quick-make/quick break , non-teasable variation of wiping contacts usually used on high voltage AC/DC type switches.

Carling’s DK/EK switch series offers knife-blade action contacts.
Carling Knife Blade Toggle Switches

Source - https://www.carlingtech.com/contacts


See also:
Common Contact Base Materials
Understanding Form A, Form B, Form C Contact Configuration
All DigiKey Switches
Webinar: AC Power Generation and Storage Using 300A G9KA-E PCB Relays

Summary

littelfuse
little fuse
littlefuse
carling technologies
carling tech
432-1095-ND
432-1285-ND
432-1292-ND
432-1322-ND
432-1088-ND
432-1122-ND
432-1290-ND
432-1252-ND
432-1289-ND
432-1284-ND
432-1300-ND
432-1271-ND
432-1293-ND
432-1291-ND
V1B1B801-6WZ00-000-ND
432-1274-ND
432-1294-ND
432-1305-ND
432-1089-ND
432-1091-ND
432-1303-ND
432-1094-ND
432-1090-ND
432-1098-ND
432-1295-ND
2266-RB201-RB-B-0-N-ND
2266-RC211-RB-B-0-N-ND
2266-62115419-0-0-N-ND
2266-62116319-0-0-N-ND
2266-TA20B-TW-B-ND
2266-LTA201-PB-B-A/125N-ND
2266-TIGL51-6S-BL-NBL-ND
2266-V1DAB60C-CMC00-000-ND
2266-V2DAB60C-CTC00-000-ND
2266-V2DAB60C-CGC00-000-ND
2266-TIGK5M-6S-BL-NBL-ND
2266-TIGL5B-6S-BL-NBL-ND
2266-VDDAS00C-CZC00-000-ND
2266-TIGM5B-6S-BL-NBL-ND
2266-VLDAB60C-CMC00-000-ND
432-1253-ND
432-1281-ND
432-1273-ND
F8926-ND
432-1276-ND
F8910-ND
432-1319-ND
62151283-0-0-N-ND
F8903-ND
F8906-ND
2266-62116419-0-9-V-ND
2266-RA201-VB-B-1-V-ND
2266-TA201-PB-B-ND
2266-62115429-0-0-N-ND
432-1141-ND
F8793-ND
432-1142-ND
2266-VJDAS00C-CZC00-000-ND
432-1235-ND
2266-VJDAB60C-CBC00-000-ND
F8886-ND
F8888-ND
2266-VLDAB60C-CBC00-000-ND
F8885-ND
F8878-ND
F8879-ND
F8890-ND
F8891-ND
432-VLD2S004-JZZ00-000-ND
F8880-ND
F8882-ND
F8883-ND
432-TIGM5E-1S-WH-FN-ND
432-1092-ND
2266-RA901-RB-B-0-N-ND,432-1110-ND
432-1111-ND
432-1112-ND
432-1115-ND
432-1116-ND
432-1117-ND
432-1118-ND
432-1121-ND
432-1288-ND
432-1280-ND
432-1272-ND
432-1324-ND
432-1120-ND
432-1337-ND
2266-632122-2-B-JN-ND
432-1140-ND
F8791-ND
432-V1D1AN0B-A9C52-1UY-ND
F8895-ND
432-VJD1AN0B-A9C45-1UV-ND
2266-VJDAB60C-CTC00-000-ND
V1D2B60B-A9C00-000
LTILA51-6S-BL-RC-NBL/125N
TIGK721-6S-BL-NBL/ON-OFF
W18D20001-AZZ00-000
V1D2GHNB-AAC00-000
RD221-MB-B-0-N
RSCA201-VB-B-1-V
62115929-0-0-V
RGSCC201-R-B-B-E
LTA201-TR-B/125N
V8D1S00B-00000-000
L11D1S001-AZZ00-000
V1D1B60B-CMC00-000
TIGK51-6S-BL-NBL
V1B1B801-6WZ00-000
L21D1S001-AZZ00-000
V1D1G66B-00000-000
VLD1S00B-00000-000
V2D2GHNB-AAC00-000
V4D2GHNB-AAC00-000
VJD1D66B-00000-000
V8D2UHNB-AAC00-000
VGD2GHNB-AAC00-000
VLD2GHNB-AAC00-000
V1D1S00B-00000-000
RB201-RB-B-0-N
RC211-RB-B-0-N
62115419-0-0-N
62116319-0-0-N
TA20B-TW-B
LTA201-PB-B-A/125N
TIGL51-6S-BL-NBL
V1DAB60C-CMC00-000
V2DAB60C-CTC00-000
V2DAB60C-CGC00-000
TIGK5M-6S-BL-NBL
TIGL5B-6S-BL-NBL
VDDAS00C-CZC00-000
TIGM5B-6S-BL-NBL
VLDAB60C-CMC00-000
62116919-0-9-V
LRA511-RS-B/012V
L14D1S001-AZZ00-000
58312-R4
L24D1S001-AZZ00-000
58027-11
W11D2G661-A7900-000
62151283-0-0-N
58027-01
58027-04
62116419-0-9-V
RA201-VB-B-1-V
TA201-PB-B
62115429-0-0-N
1M1-DP1-R1/2-M1QE
54010
1M1-DP3-R1/2-M1QE
VJDAS00C-CZC00-000
1M1-DP5-R6/2-2M1GE
VJDAB60C-CBC00-000
57000-04
57000-23
VLDAB60C-CBC00-000
57000-01
56000-04
56000-08
57004-10
57006-01
VLD2S004-JZZ00-000
56012-04
56300-01
56300-02
TIGM5E-1S-WH-FN
V6D2GHNB-AAC00-000
RA901-RB-B-0-N
RA901-RB-B-A-N
RA901-RB-B-F-N
RA901-VB-B-0-V
RA901-VB-B-1-V
RA901-VB-B-2-V
RA901-VB-B-9-V
RC911-RB-B-0-N
RB911-RB-B-0-N
LRA211-RS-B/125N
L12D1S001-AZZ00-000
W24D20001-AZZ00-000
RA901-VW-W-1-V
HR26D1A11BW1-11-YKUS1
632122-2-B-JN
1M1-SP5-R1/2-M1QE
54003
V1D1AN0B-A9C52-1UY
57014-03
VJD1AN0B-A9C45-1UV
VJDAB60C-CTC00-000