W199X-1 - Magnecraft Electric

APPLICA

APPLICATION D

TION DA

6...4

9/04

HOW REED RELAYS WORK

The term reed relay covers dry reed relays and mercury-

wetted contact relays, all of which use hermetically sealed

reed switches. In both types, the reeds (thin, flat blades)

serve multiple functions - as conductor, contacts, springs,

and magnetic armatures.

DRY REED RELAYS

Dry reed relays have become an important factor in the relay

field. They have the advantage of being hermetically sealed

and resistant to atmospheric contamination. They have fast

operate and release times and when operated within their

rated contact loads, have very long life. A typical dry reed

switch capsule is shown in Figure 1.

SUPPORTING GLASS SUPPORTING

TERMINAL CAPSULE TERMINAL

NORMALLY OPEN CONTACTS

In the basic SPST-NO design, two opposing blades are

sealed into a narrow glass capsule and overlapped at their

free ends. The contact area is plated typically with rhodium

to produce a low contact resistance when contacts are

drawn together. The capsule is made of glass and filled

with a dry inert gas and then sealed. The capsule is

surrounded by an electromagnetic coil. When the coil is

energized, the normally open contacts are brought together;

when the coil voltage is removed, the blades separate by

their own spring tension. Some reeds contain permanent

magnets for magnetic biasing to achieve normally closed

contacts (SPST-NC) or SPDT contact combinations. The

current rating, which is dependent upon the size of the blade

and the type and amount of plating, may range from low level

to 1 amp. Effective contact protection is essential when

switching loads other then dry resistive loads.

CONTACT COMBINATIONS.

The switches used in dry reed relays provide SPST-NO,

SPST-NC, SPDT contact combinations. The SPST-NO

corresponds with the basic switch capsule design (Fig.1).

The SPST-NC results from a combination of the SPST-NO

switch and a permanent magnet strong enough to pull the

contacts closed but able to open when coil voltage is applied

to the relay coil. In typical true SPDT designs, the armature

is mechanically tensioned against the normally closed contact,

and is moved to the normally open contact upon application

of a magnetic field. The SPDT contact combination can also

be achieved by joining a SPST-NO switch with an appropriately

adjusted SPST-NC switch, and jumping one side of both

switches together to form the movable contact system.

Latching contacts, defined as contacts which remain in the

position to which they were driven, and stay in that position

when coil power is removed from the relay coil.

Latching switches are manufactured by using a SPST-NO

contact, and biasing it with a permanent magnetic that is

strong enough to hold the contacts closed, but not strong

enough to hold the contact closed when coil power is

applied to the coil. The switching process is than reversed

by simply reversing the relay coil polarity to close the

switch, or by employing a second coil with a reverse field.

MAGNETIC FIELDS

Reed relays in general can be characterized as susceptible

to the influences of external magnetic fields. It is important

to keep reed relays at a proper distance from each other

because of the possibility of magnetic-interaction between

them. Proper magnetic shielding must be used to contain

stray magnetic fields. When installing reed relays into

equipment, one should be aware of the devices within that

equipment which can produce magnetic fields. The relays

being installed into that equipment should be positioned as

far away as possible from any stray magnetic fields and

should be shielded to prevent false operations.

ELECTRICAL CHARACTERISTICS

SENSITIVITY: The input power required to operate dry reed

relays is determined by the sensitivity of the particular reed

switch used, by the number of switches operated by the

coil, by the permanent magnet biasing (if used), and the

efficiency of the coil and the effectiveness of its coupling

to the blades. Minimum input required to effect closure

ranges from the very low milliwatt level for a single

sensitive capsule to several watts for multipole relays.

OPERATE TIME: The coil time constant, overdrive on the

coil, and the characteristics of the reed switch determine

operate time. With the maximum overdrive voltage applied

to the coil, reed relays will operate in approximately the

200 microsecond range. When driven at rated coil voltage,

usually the relays will operate at about one millisecond.

RELEASE TIME: With the coil unsuppressed, dry reed

switch contacts release in a fraction of a millisecond.

SPST-NO contacts will open in as little as 50 microseconds.

Magnetically biased SPST-NC and SPDT switches reclose

from 100 microseconds to 1 millisecond respectively. If the

relay coil is suppressed, release times are increased.

Diode suppression can delay release times for several

milliseconds, depending on coil characteristics, coil

voltage, and reed release characteristics.

CONTACT BOUNCE

Dry reed contacts bounce on closure as with any other

hard contact relay.The duration of bounce on a Dry reed

switch is typically very short, and is in part dependent on

drive level. In some of the faster devices, the sum of the

operate time and bounce is relatively constant. As drive is

increased, the operate time decreases with bounce time

increasing. The normally closed contacts of a SPDT switch

bounce more then the normally open contacts.

Magnetically biased SPST-NC contacts exhibit essentially

the same bounce characteristics as SPST-NO switches.

Figure 1. Construction of Switch Capsule

of Typical Dry Reed switch (SPST-NO)

REED RELAYS

APPLICA

APPLICATION D

TION DA

CONTACT RESISTANCE

The reeds (blades) in a dry reed switch are made of magnetic

material which has a high volume resistivity, terminal-to-

terminal resistance is somewhat higher than in some other

types of relays. Typical specification limits for initial resistance

of a SPST-NO reed relay is 0.200 ohms max (200 milliohms).

INSULATION RESISTANCE

A dry reed switch made in a properly controlled internal

atmosphere will have an insulation resistance of 1012 to 1013

ohms or greater. When it is assembled into a relay, parallel

insulation paths reduce this to typical values of 1013 ohms.

Depending on the particular manner of relay construction,

exposure to high humidity or contaminating environments

can appreciably lower final insulation resistance.

CAPACITANCE

Reed capsules typically have low terminal-to-terminal

capacitance. However, in the typicall relay structure where

the switch is surrounded by a coil, capacitance from each

reed to the coil act to increase capacitance many times. If

the increased capacitance is objectionable, it can be reduced

by placing a grounded electrostatic shield between the switch

and coil.

DIELECTRIC WITHSTAND VOLTAGE

With the exception of the High-Voltage dry reed switches

(capsules that are pressurized or evacuated), the dielectric

strength limitation of relays is determined by the ampere

turn sensitivity of the switches used. A typical limit is 200

VAC. The dielectric withstand voltage between switch and

coil terminals is typically 500 VAC.

THERMAL EMF

Since thermally generated voltages result from thermal

gradients within the relay assembly, relays built to

minimize this effect often use sensitive switches to reduce

required coil power, and thermally conductive materials to

reduce temperature gradients. Latching relays, which may

be operated by a short duration pulse, are often used if the

operational rate is not changed for longer periods of time

because coil power is not required to keep the relay in the

on or off position after the initial turn on or turn off pulse.

NOISE

Noise is defined as a voltage appearing between terminals

of a switch for a few milliseconds following closure of the

contacts. It occurs because the reeds (blades) are moving

in a magnetic field and because voltages are produced within

them by magnetostrictive effects. From an application

standpoint, noise is important if the signal switched by the

reed is to be used within a few milliseconds immediately

following closure of the contacts. When noise is critical in

an application, a peak-to-peak limit must be established by

measurement techniques, including filters which must be

specified for that particular switching application.

ENVIRONMENTAL CHARACTERISTICS

Reed relays are used in essentially the same environments as

other types of relays. Factors influencing their ability to function

would be temperature extremes beyond specified limits

VIBRATION

The reed switch structure, with so few elements free to move,

has a better defined response to vibration than other relay

types. With vibration inputs reasonably separated from the

resonant frequency, the reed relay will withstand relatively high

inputs, 20 g's or more. At resonance of the reeds, the typical

device can fail at very low input levels. Typical resonance

frequency is 2000 hz.

SHOCK

Dry reed relays will withstand relatively high levels of shock.

SPST-NO contacts are usually rated to pass 30 to 50 g's,

11 milliseconds, half sign wave shock, without false

operation of contacts. Switches exposed to a magnetic

field that keep the contacts in a closed position, such as in the

biased latching form, demonstrate somewhat lower resistance

to shock. Normally closed contacts of mechanically biased

SPDT switches may also fail at lower shock levels.

TEMPERATURE

Differential expansion or contraction of reed switches and

materials used in relay assemblies can lead to fracture of

the switches. Reed relays are capable of withstanding

temperature cycling or temperature shock over a range of

at least -50C to + 100C. These limits should be applied to

the application to prevent switch failure.

CONTACT PROTECTION

Tungsten lamp, inductive and capacitive discharge load are

extremely detrimental to reed switches and reduce life

considerably. Illustrated below are typical suppression

circuits which are necessary for maximum contact life.

INPUT R INPUT R

Figure 3

Initial cold filament turn-on current is often 16 times higher

than the rated operating current of the lamp. A current limiting

resistor in series with the load, or a bleeder resistor across the

contacts will suppress the inrush current. The same circuits

can be used with capacitive loads, as shown in Figure 3.

INPUT INPUT

Figure 4

DC inductive loads call for either a diode or a thyristor to be

placed across the load. These circuits are necessary to protect

the contacts when inductive loads are to be switched in a

circuit, as shown in Figure 4.

6...5

9/04

REED RELAYS

SIP & DIP MINIATURE REED RELAYS

0.750 MAX.

(19.0)

0.290 MAX.

(7.36)

0.110

(2.79)

0.010 TYP.

(0.25)

0.030 TYP.

(0.762)

0.260 MAX

(6.60)

0.290 MAX.

(7.36)

0.075 TYP.

(1.90)

0.020 TYP.

(0.51) 0.200 TYP.

(5.08)

0.600 TYP.

(15.2)

0.140TYP.

(3.55)

PIN NO.1

INDICATOR

OUTLINE DIMENSIONS

DIMENSIONS SHOWN IN INCHES & (MILLIMETERS)

117SIP

0.750 MAX.

(19.0)

0.300 MAX.

(7.62)

0.010 TYP.

(0.25)

0.275 MAX.

(6.98)

0.020 TYP.

(0.51)

0.020 TYP.

(0.51)

0.600 TYP

(15.2)

0.150 TYP.

(3.81)

0.400

(10.1)

0.100 TYP.

(2.54)

107DIP, 171DIP, 172DIP(SPDT)

PHONE: (843) 393-5778 FAX: (843) 393-4123 EMAIL: info@magnecraft.com

Not applicable

-40

+85

-40

+105

50,000,000

100,000,000

Any

Glass

Thermo set plastic

SHOCK RESIS

SHOCK RESIST

TANCE

ANCE

Functional:

TEMPER

TEMPERA

ATURE

TURE

Operating, AC Lower:

Operating, AC Upper:

Operating, DC Lower:

Operating, DC Upper:

Storage, Lower:

Storage, Upper:

LIFE EXPECT

LIFE EXPECTANC

ANCY

Electrical @ Rated Load (AC1):

Mechanical @ no Load :

MISCELLANEOUS

Operating Position:

Insulation Material:

Enclosure Material:

Cover Protection Category:

Weight:

UNITS

gs

ºC

operations

grams

COIL

Pull-in Voltage AC (50/60 Hz):<

Pull-in Voltage DC:<

Dropout Voltage AC (50/60 Hz):>

Dropout Voltage DC:>

Maximum Voltage:

Resistance:

Coil Power AC (60 Hz):

Coil Power DC:

CONT

CONTA

ACTS

CTS

Contact Material:

Contact Rating AC Amperes (AC1):

Contact Rating AC Voltage:

Contact Rating DC Amperes (DC1):

Contact Rating DC Voltage:

Contact Rating :

General Purpose Rating (75%-80%):

Horse Power (AC):

Pilot Duty (60 Hz):

VA Rating Make:

VA Rating Break:

Minimum Recommended Load:

TIMING

Operate Time:

Release Time:

DIELECTRIC S

DIELECTRIC STRENGTH

TRENGTH

Coil to Contacts:

Across Open Contacts:

Pole to Pole:

Contacts to Frame:

Insulation Resistance:

VIBR

VIBRA

ATION RESIS

TION RESIST

TANCE

ANCE

Functional:

Not applicable

110

Not applicable

117SIP, 107DIP: 0.050 to 0.288

171DIP: 0.050 to 0.270

172DIP: 0125 to 0.540

RHODIUM

117SIP, 107DIP, 171DIP: 0.5

172 DIP: 0.25

117SIP, 107DIP: 120

171DIP, 172 DIP: 60

0.5

100

117SIP, 107DIP, 171DIP: 10

172 DIP: SPDT 4, DPDT 10

Not applicable

10 or 0.05 Watt

500

150

Not applicable

1000 @ 500

UNITS

% of nominal

% ±

V rms

megohms

minimum

@VDC

gs

0.082 TYP.

(2.09)

0.800 MAX.

(20.32)

0.046 TYP.

(1.19)

0.025

(0.635)

0.400 MAX.

(10.16)

0.100 TYP.

(2.54)

0.600 TYP.

(15.2)

0.400 MAX.

(10.16)

0.125 TYP.

(3.17)

PIN NO.1

LOCATION

0.3 ±0.003

(7.62)

172DIP (DPDT)

GENER

GENERAL SPECIFIC

AL SPECIFICA

ATIONS (@

TIONS (@ 25

ºC

)

6...6

9/04

WIRING DIAGRAM

(TOP VIEWED )

SPST NO OR NC, DPST NO, 0.5 AMP

W117SIP-1

W117SIP-3

W117SIP-5

W117SIP-22

W117SIP-23

W117SIP-24

W117SIP-6

W117SIP-8

W117SIP-10

W117SIP-18

W117SIP-25

W117SIP-26

W107DIP-1

W107DIP-3

W107DIP-4

W107DIP-5

W107DIP-7

W107DIP-8

W171DIP-2

W171DIP-4

W171DIP-5

W171DIP-7

W171DIP-9

W171DIP-10

W171DIP-12

W171DIP-14

W171DIP-15

W171DIP-17

W171DIP-19

W171DIP-20

W171DIP-21

W171DIP-23

W171DIP-24

W171DIP-25

W171DIP-27

W171DIP-28

500 W

1000 W

2000 W

500 W

1200 W

2200 W

500 W

1000 W

2000 W

500 W

1200 W

2200 W

500 ý

1000 W

2000 W

500 W

1000 W

2000 W

500 W

1200 W

2200 W

500 W

1000 W

2200 W

200 W

1200 W

2200 W

500 W

1200 W

2200 W

500 W

1000 W

2200 W

500 W

1000 W

2200 W

144

288

120

270

144

288

120

220

144

288

144

288

120

270

144

270

120

270

120

270

144

270

144

270

NOMINAL

POWER

(mW)

STANDARD

PART

NUMBERS

NOMINAL

INPUT

VOLTAGE

NOMINAL

RESISTANCE

(OHMS)

SPST - N. O., 0.5 AMP

SPST - N. C., 0.5 AMP

SPST - N. O. WITH CLAMPING DIODE, 0.5 AMP

1 3 5 7 1 3 5 7

SPST - N. C. WITH CLAMPING DIODE, 0.5 AMP

1 3+ 5- 7 1 3+ 5- 7

SPST - N. C., 0.5 AMP

SPST - N. C. WITH CLAMPING DIODE, 0.5 AMP

DPST - N. O., 0.5 AMP

DPST - N. O. WITH CLAMPING DIODE, 0.5 AMP

SEE END OF SECTION 6 FOR CROSS REFERENCE

PHONE: (843) 393-5778 FAX: (843) 393-4123 EMAIL: info@magnecraft.com

SIP & DIP MINIATURE REED RELAYS

SPST - NO SPST - NC

117SIP

107DIP

SPST - NO SPST - NC

SPST - NO SPST - NO

SPST - NC SPST - NC

DPST - NO DPST - NO

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

WITH DIODE WITH DIODE

WITH DIODE

171DIP

WHEN SPACING SIP

RELAYS, THE RELAYS

REQUIRE 1/2 INCH

SPACING FROM THE

SIDE OF THE

ADJACENT RELAYS.

SPST - N. O. WITH CLAMPING DIODE, 0.5 AMP

SPST - N. O., 0.5 AMP

SPST - N. O. WITH CLAMPING DIODE, 0.5 AMP

SPST - N. O., 0.5 AMP

6...7

9/04

COIL MEASURED @ 25 ºC

WIRING DIAGRAM

(TOP VIEWED )

W172DIP-1

W172DIP-3

W172DIP-4

W172DIP-5

W172DIP-7

W172DIP-8

W172DIP-31

W172DIP-33

W172DIP-34

W172DIP-35

W172DIP-37

W172DIP-38

W172DIP-141

W172DIP-145

W172DIP-146

W172DIP-147

W172DIP-149

W172DIP-150

W172DIP-17

W172DIP-19

W172DIP-20

W172DIP-21

W172DIP-23

W172DIP-24

200 W

500 W

2200 W

200 W

500 W

2200 W

200 W

500 W

2200 W

200 W

500 W

2200 W

200 W

1000 W

3200 W

200 W

1000 W

3200 W

46 W

266 W

1066 W

46W

266 W

1066 W

125

300

270

125

300

270

125

290

270

125

290

270

125

144

180

125

144

180

540

NOMINAL

POWER

(mW)

STANDARD

PART

NUMBERS

NOMINAL

INPUT

VOLTAGE

NOMINAL

RESISTANCE

(OHMS)

SPDT, 0.25 AMP

SPDT WITH CLAMPING DIODE, 0.25 AMP

SPDT, 0.25 AMP

SEE END OF SECTION 6 FOR CROSS REFERENCE

PHONE: (843) 393-5778 FAX: (843) 393-4123 EMAIL: info@magnecraft.com

DIP MINIATURE REED RELAYS

SPDT SPDT

WITH DIODE

SPDT WITH CLAMPING DIODE, 0.25 AMP

DPDT WITH CLAMPING DIODE

, 0.25 AMP

DPDT, 0.25 AMP

SPDT NO, DPDT, 0.25 AMP

172DIP

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7 1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

1 2 6 7

14 13 9 8

SPDT SPDT

WITH DIODE

SPDT SPDT

WITH DIODE

DPDT DPDT

WITH DIODE

WHEN SPACING DIP RELAYS, THE RELAYS

REQUIRE 1/2 INCH SPACING FROM THE SIDE

OF THE ADJACENT RELAYS.

COIL MEASURED @ 25 ºC

6...8

9/04

172DIP