Page 1
30
0
(Seconds)
TB1
1
2
3
1
2
3
TB2
1/4A
F1
4
5
6
60
7
50
40
80
70
100
90
30
20
0
10
300-3600 PPM
15-60 PPM
60-300 PPM
UNDER
OVER
Model 250 Speed Sensor
St artup Del ay
15
Mag-Con Engineering
10
5
20
25
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CK
K
C
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Model 250 Rotary Speed Sensor
Installation and Operation Instructions
1.0 PRINCIPLE OF OPERATION
The Badger Magnetics Rotary Speed Sensor
system consists of a speed sensor board, a sense
head, and a magnetic “mark”. The mark is mounted
on a rotating or moving device, such as a pulley or
belt, and the sense head is mounted on a stationary
section in such a way that the mark periodically
passes parallel to the face of the sensor. The sense
head is connected to the speed sensor board through
a shielded cable. The speed sensor board contains a
single relay with two Form-“C” contacts that are
available for connection to external alarm or
shutdown circuits. This relay is energized during
normal operation, and so provides fail-safe
operation. If power is disconnected from the board,
or if an internal board failure occurs, the relay will
de-energize, causing a fault condition.
In operation, the speed sensor board measures
the period between mark passes and compares it
with a preset set point. With the speed sensor board
set for Under Speed detection, if the period between
mark passes exceeds the set point (the rotating
machine is running too slow), the relay on the speed
sensor board will de-energize, operating the alarm
or shutdown circuit. With the speed sensor board set
for Over Speed detection, if the period between
mark passes is less than the set point (the rotating
machine is running too fast), the relay will de-
energize. In addition, in the Over Speed mode, if no
mark passes are detected for 5 seconds, the relay
will de-energize. This “missing head pulse” detector
provides a fail-safe mode in the event that the sense
head is damaged, the cable is broken, or the mark
becomes damaged or dislodged.
If dual speed detection is required, such as a
separate alarm and shutdown speed, or a high and
low speed limit is needed, a second modified speed
sensor may be connected to the same sense head. If
a meter indication of actual speed is required,
Badger Magnetics can supply a separate tachometer
board that may also be connected to the same sense
head. Consult the factory for information.
2.0 DESCRIPTION OF THE SYSTEM
2.1
Control Circuit
The control circuit is mounted on a printed
circuit board. Power input, sense head wires, and
output connections are made to two screw terminal
strips, TB1 and TB2.
The output relay is dust-tight, and provides two
Form-“C” contacts, each rated at 10A resistive, or
1/3 HP at 120VAC.
The board has two operating controls, the
setpoint adjustment knob, the startup delay control,
and two user-selectable jumpers, one for operating
