Edwards Signaling 301-BT Series - Manual (Page 2)

2 / 6 P/N 13924 • REV D • REB 27FEB13
Caution: When not used with a Sentrol INT relay particular
care must be taken to determine the actual load of the switch
circuit. High voltage transients from coils, motors, contactors
and solenoids must be considered. Transient protection, such
as back-to-back zener diodes (TransZorb®) or an RC network,
is recommended for such loads to ensure that maximum
ratings of the switch are not exceeded. Not recommended to
be used with tungsten filament loads because of high current
inrush surges. Line capacitance and load capacitance must be
considered.
Excessive line capacitance can be caused by cable lengths
over 50' when using a maximum 48 VAC. A resistor can be
added in series to limit the inrush current (at least 48 ohms for
24 Volt applications).
The resistor can be added in series just before the load.
The voltage drop and the power rating of the resistor must be
considered.
Voltage drop = I•R;
Watts = I2•R (I = maximum continuous current of the load).
6. When mounting the switch on an ungrounded machine,
ground the switch housing by connecting your ground lead to
one of the switch mounting screws.
Figure 2: Switch/Actuator position
Figure 3: Mounting configurations
Figure 4: Circuits
*Circuits shown with magnet actuator away from switch.
S1,S5 Normally open reed switch, closed when actuator is within
0.6"
S2, S3 Normally open reed switches, will close if misaligned or
tampered with a standard magnet
S4 Biased closed reed switch, open when actuator is between
0.3" and 0.6"
N.O. circuit: Black and white wires.
N.C. biased tamper circuit: Red and blue wires.
N.O. monitor circuit: Orange and brown wires.