Red Lion MP User Manual

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MAGNETIC PICKUPS & IN-LINE PREAMPLIFIER

SIMPLE, RELIABLE & ECONOMICAL PULSE GENERATORS FOR:

SPEED SWITCHES
DIGITAL TACHOMETERS
FREQUENCY TO D.C. CONVERTERS

FEATURES INCLUDE

 SELF-GENERATING, NO EXT. POWER NEEDED

 WIDE OPERATING TEMPERATURE RANGE

 EPOXY ENCAPSULATED, MECHANICALLY RUGGED

 IMPERVIOUS TO DIRT, OIL & WATER

 NO MAINTENANCE REQUIRED

 LOW COST

 M12 CONNECTOR (MODEL SPECIFIC)

Bulletin No. MP-L

Drawing No. LP0020

Released 02/10

DESCRIPTION OF OPERATION

A Magnetic Pickup consists of a permanent magnet, a pole-piece, and a
sensing coil all encapsulated in a cylindrical case. An object (target) of iron,
steel, or other magnetic material, passing closely by its pole-piece causes
distortion of the magnetic flux field passing through the sensing coil and pole­piece, which in turn generates a signal voltage. The magnitude of the signal
voltage depends on the relative size of the magnetic target, its speed of
approach, and how close it approaches. The polarity of the signal depends on
whether the target is moving toward or away from the pole-piece.

Magnetic Pickups are most frequently used to sense passing teeth on a gear,
sprocket, or timing belt wheel, to bolt-heads, key-ways, or other moving
machine mounted targets. Typical targets and resulting signal wave forms are
shown below in Fig. 1.

SELECTING A MAGNETIC PICKUP

Selecting a magnetic pickup is a matter of matching a pickup to a gear (or
other target), to provide enough input signal to a tachometer, speed-switch, or

other device for operation at the required minimum speed. The open-circuit
output from a magnetic pickup is directly proportional to speed, and once the
minimum operating speed conditions have been met, excess signal will always
be available at higher speeds.

The “1-Volt Threshold Speed” column in the Application and Ordering Table
(next pg.) provides a convenient guide for estimating minimum operating
speeds. This value is the linear surface-speed of a reference gear required to
generate a 1-Volt peak, open-circuit output at an air-gap of 0.005". The
reference gear listed for each pickup is near the optimum size for that pickup,
as defined by the criteria in Fig. 1B. The RPM listed is for a reference gear with
60 teeth running at that surface-speed. Gears with larger teeth provide about the
same or somewhat more output at the same surface-speed, while gears with
smaller teeth or fewer number of teeth yield lower outputs. Figures 1C - 1F need
a very high surface speed to generate a 1-Volt peak. The “Minimum Gear Size”
column lists the Diametral Pitch size at which the output drops to 40-60% of the
output when the reference gear is used. Gears with very small teeth in relation
to the pole-piece diameter, deliver greatly reduced outputs, as shown in Fig. 1A.
Threshold outputs when using targets other than gear teeth can be estimated by
their relative size with respect to the reference gear teeth. For more information

(A)

MAG.

SMALL

PICKUP DIA.=d

GEAR GEAR

(B)

OPTIMUM

d

POLE

(C)

LARGE

GEAR

d

3d

(D)

SHAFT

KEYWAY

on gears, definitions and relationships, see the Sensing Gears Bulletin.

The 1-Volt Threshold Speeds are based on a 0.005" air-gap. In applications
where this air-gap cannot be maintained or where the air-gap can vary due to
eccentricity of the sensing gear, a correction factor can be applied from the
curve in Fig 2. The effect of electrical loading is usually minimal at low speeds
and low output frequencies, however, output voltage drop due to loading at high
frequency or with low impedance inputs can be estimated based on the Output
Impedance data.

Note: Magnetic Pickups are used primarily for tachometer and other speed

related functions. They are not normally used for counting since loss of

counts will occur at low speeds. Therefore, counters are not designed to

accept outputs directly from conventional magnetic pickups. In special

applications where counting occurs only at running speed or where low-

speed count loss is acceptable, a Model ASTC can be used, or a different type

of sensor can be used as a substitute.

TYPICAL APPLICATION EXAMPLE

A Digital Tachometer, with an input sensitivity of 0.25 V is to be used with a
Magnetic Pickup and gear to indicate speed down to 75 RPM. What are the
alternative choices?

Since the input voltage required by the tachometer is only 0.25 V, the surface
speeds and reference gear RPM’s required would only be 2 of the 1-Volt
Threshold Speeds listed. The MP-25TA with a 60-tooth, 24 D.P. reference gear
would obviously fall short since this combination will not develop 0.25 V until
the reference gear speed reaches 250 RPM.

The MP-37CA with the 60-tooth, 20 D.P. reference gear would both prove
suitable since they would deliver the required 0.25 V at 50 and 45 RPM
respectively. They would also provide some additional margin for air-gap
variation. The curve of Fig. 2 shows a typical output drop of about 25% when
the air-gap is increased from 0.005" to 0.0075". Since the minimum operating
speed in this application is 75 RPM, the additional sensitivity can be traded for
a wider air-gap allowance.

The MP-62TA and MP-75TX with their respective reference gears would
allow operation at even lower speeds. With both of these pickups it would be
possible to drop to a smaller gear pitch for this application.

100

(E)
BOLT
HEAD

CAM

(F)

75

50

+

OUTPUT

VOLTAGE

-

TRAILING

EDGE

LEADING

EDGE

LEADING

EDGE

TRAILING

EDGE

25

REL. OUTPUT %

0

0 5 10 15 20 25

AIR GAP (INCHES x .001)

FIG. 1 OUTPUT WAVEFORMS WITH VARIOUS TARGET SHAPES & SIZES FIG. 2 TYPICAL OUTPUT/AIR-GAP

1

MAGNETIC PICKUP APPLICATION & ORDERING INFORMATION

N.C.

MODEL NO. DIMENSIONS

0.313"
(7.95)

REF.

MP25TA

1/4"-40 UNS-2A THREAD

(11.15)

REF.

MP37TA

3/8"-24 UNF-2A THREAD

3/8"-24 UNF-2A THREAD

MP37TAC1

2.50 ±0.03" (63.5 ±0.76)

MP37CA

+0.000

(9.474 )

-0.127

0.625"

(15.88)

MP62TA

MP62TAC1

2.125 ±0.01"

0.625"

(15.88)

MP62TB00

1.25"

(31.75)

3/4" 20 UNEF-2A THREAD

0.625" (15.88) REF.

PIN 3

PIN 4

0.5" INTERNAL PIPE THREAD

MP-25TA

MP-37TA

MP-37TAC1

MP-37CA

MP-62TA

MP-62TAC1

MP-62TB

MP-75TX
Explosion

Proof (3)

0.040" (1.016)

DIA. POLE TIP

0.02" (0.51)

0.094" (2.387)

DIA. POLE TIP

0.02" (0.51)

0.094" (2.387) DIA.
POLE TIP

0.02" (0.51)

0.094 ±0.005"
(2.39 ±0.13)

DIA. POLE TIP

FLUSH WITH CASE

0.115 ±0.015
(2.92 ±0.38)

DIA. POLE TIP

0.02 (0.50)

0.02 (0.50)

0.115 ±0.015
(2.92 ±0.38)

DIA. POLE TIP

5/8-18UNF-2A THREAD

BLIND END SHELL

0.106 (2.69) DIA.

EFFECTIVE POLE TIP

BLIND END SHELL

0.187" (4.75)

DIA. POLE PIECE

0.687 ±0.01"

(17.45 ±0.254)

0.812 ±0.01" 0.439"

(20.62 ±0.25)

0.812 ±0.01"

(20.62 ±0.25)

1.60 ±0.025" (40.64 ±0.635)

+0.000"

0.373"

-0.005"

2.125 ±0.01"

(53.98 ±0.25)

5/8" - 18 UNF-2A THREAD

2.00 ±0.01"

(50.8 ±0.254)

(53.98 ±0.25)

5/8" - 18 UNF-2A THREAD

1.875"

(47.63)

6.0"

(152.4)

MIN.

6.0"

(152.4)

MIN.

PIN 3

PIN 4

10' 0"

(3048)

MIN.

PIN 2

45°

PIN 1

10' 0"

(3048)

MIN.

36.0"

LEAD LENGTH MIN.

FLEXIBLE LEADS

28 AWG.

VINYL LEADS

28 AWG.

VINYL LEADS

PIN 1

+2.0"

8.0"

-0.0"
+50.8

(203.2 )

-0.0

20 AWG.

VINYL LEADS

VINYL JACKETED
SHIELDED CABLE

See Note 7
for pin-out
information

VINYL JACKETED
SHIELDED CABLE

(914.4)

18 AWG.

PIN 2

45°

24 AWG.

24 AWG.

See Note 7
for pin-out
information

THRESHOLD

60T 24 D.P.

60T 20 D.P.

60T 20 D.P.

60T 20 D.P.

60T 16 D.P.

60T 16 D.P.

60T 16 D.P.

60T 10 D.P.

1-VOLT

SPEED (1)

135 in/sec
1000 RPM

Ref. Gear

33 in/sec
200 RPM

Ref. Gear

33 in/sec
200 RPM

Ref. Gear

30 in/sec
180 RPM

Ref. Gear

10 in/sec

50 RPM

Ref. Gear

10 in/sec

50 RPM

Ref. Gear

20 in/sec
100 RPM

Ref. Gear

30 in/sec
100 RPM

Ref. Gear

MINIMUM

GEAR

PITCH (2)

TEMP.

RANGE

°C

OUTPUT

IMPENDANCE

48 D.P. -40 to +107 130 Ω ±20%

15 mH

32 D.P. -40 to +107 340 Ω ±20%

44 mH

32 D.P. -40 to +107 340 Ω ±20%

44 mH

32 D.P. -40 to +107 300 Ω ±30%

65 mH

24 D.P. -40 to +107 1200 Ω ±20%

400 mH

24 D.P. -40 to +107 1200 Ω ±20%

400 mH

24 D.P. -40 to +107 1200 Ω ±20%

400 mH

12 D.P. -73 to +93 230 Ω ±20%

100 mH

PART NUMBER

MP25TA00

MP37TA00

MP37TAC1

*

MP37CA00

MP62TA00

MP62TAC1

*

MP62TB00

MP75TX00

NOTES:

1) Surface speed of listed reference gear to produce 0.8 volt peak min., open­circuit output @ 0.005" air-gap.

2) Gear pitch where output will drop to 40-60% of that generated by the
reference gear size, at the same surface speed.

3) UL Listed CSA Certified, Class I Group A, B, C and D; Class II Group E, F
and G. (AI-TEK Instruments) PN#AIRPAX/70085-1010-005, UL File
#E40545 (N), CSA File #042648.

4) Polarity, all pickups: white output lead goes positive with respect to black
when target approaches pole.

5) 2-Wire shielded cable is recommended for all magnetic pickup outputs.
Connect the shield to the “COMMON” or “GROUND” terminal of the
instrument being used and leave the shield un-connected at the pickup.

ORDERING INFORMATION

The following cables are for use with magnetic pickups MP37TAC1 and MP62TAC1, which have

M12 connectors.

MODEL NO. DESCRIPTION PART NUMBERS

CCM CCM12S01Mating Cable With M12 Connector, 1 Meter In Length

Red Lion Controls
Headquarters
20 Willow Springs Circle
York PA 17406
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Red Lion Controls

Europe

Printerweg 10

NL - 3821 AD Amersfoort

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Fax [phone]

Magnetic Pickup signal leads should never be run in conduit, troughs, or
bundles with other power or control voltage lines.

6) Lead length of magnetic pickup should not be extended. An in-line pre­amplifier (ASTC) can be placed on the end of the provided length which
would allow longer length after the in-line pre-amplifier.

7) M12 unit color codes for 1 meter cable is:

PIN 3 - Blue (-)
PIN 4 - Black (+)
PIN 2 - NC
PIN 1 - NC

Red Lion Controls

India

54, Vishvas Tenement

GST Road, New Ranip,

Ahmedabad-382480 Gujarat, India

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PIN 3

-

PIN 4

+

PIN 2

N.C.

45°

PIN 1

Red Lion Controls

Unit 101, XinAn Plaza

Building 13, No.99 Tianzhou Road

ShangHai, P.R. China 200223

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China