Edwards Signaling Series 300 Installation Sheet
GuardSwitch Series 300
Safety Interlock Switch 301-BT
Caution: When used without 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 for use with tungsten filament loads because of high
current inrush surges. Line capacitance and load capacitance must be
considered.
Installation Sheet
Description
The GuardSwitch Series 300 Safety Interlock Switch 301-BT is
designed for use with safety monitored relays or monitored circuits. To
achieve the optimum defeat resistant features of the switch, both the
switch circuit (Circuit 1) and the tamper circuit (Circuit 2) must be
connected. An optional third circuit can be provided to indicate at the
panel which guard is open.
Notes
• Environmental: Pollution Degree II.
• Correct use of this control device is an essential part of proper
machine cycle control.
• Failure to follow all instructions could lead to serious bodily injury
or death.
• Maintenance to be done by qualified personnel only.
• The connecting cables between the INT devices and the switches
must be located in an IP 23 type enclosure (minimum).
• The mounting for the switch and the actuator magnet must be
accomplished per this specification.
• Nonremovable hardware must be used for installation.
• The housing of the switch must be connected to the PE (primary
earth) ground circuit via a lock washer on the mounting screw. The
PE ground symbol must be placed adjacent to the screw.
To verify switch operation with an ohmmeter:
Set range at 20 MΩ (switches with triac output, set range at 20 kΩ).
For a normally open switch, the meter will read a high impedance with
the actuator away. It will read very high to infinity range (triac switches
will read high kΩ to infinity range) with the actuator within sense range.
You will see the opposite reading for a normally closed switch.
Excessive line capacitance can be caused by cable lengths over 50 ft.
when using a maximum 48 VAC. A resistor can be added in series to
limit the inrush current (at least 48 Ω for 24 V 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
Wattage = I² × R (I = maximum continuous current of the load)
To install the switch:
1. Position the switch and actuator so the labels are reading in the
same direction (see Figure 2).
2. Mount the switch on the stationary frame of the machine and
mount the actuator on the moveable guard, door, or gate. Keep the
switch and actuator within the listed sense range. See “Ordering
information” on page 4 for sense ranges. See Figure 3 for
recommended mounting configurations.
3. Mounting on a ferrous material will affect the sense range a
minimum of 50%. However, a 1/4 in. nonferrous spacer positioned
under the magnet and/or switch should restore most of the lost
sense range.
4. For best protection against operator defeat, mount with
nonremovable screws, bolts, or nuts. See ordering information for
details.
5. 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 1: Dimensions
Installation
Use nonremovable screws, bolts, or nuts to mount the switch and
actuator. Do not over-torque mounting hardware. See Figure 1 for
dimensions.
P/N 13924 • REV F • ISS 09SEP15 1 / 4
Figure 2: Switch/actuator position
S1,
S2, S3
S4
NO
NC
NO
Circuits*
without LED
Circuits*
with optional LED
S1
S2
S3
S5
BLK
D1
Optional LED
WHT (or YLW)
ORG
BRN
RED
CIR. 3
CIR. 2
D2
S5
CIR. 2
S1
S2
S3
S4
S4
BLK
ORG
BRN
RED
CIR. 3
CIR. 1
WHT (or YLW)
BLUE (or GRN)
CIR. 1
BLUE (or GRN)
Figure 3: Mounting configurations
Figure 4: Circuits
*Circuits shown with magnet actuator away from switch.
S5 Normally open reed switch, closed when
actuator is within 0.6"
Normally open reed switches, will close if
misaligned or tampered with a standard
magnet
Biased closed reed switch, open when
actuator is between 0.3" and 0.6"
circuit Black, white, or yellow wires.
biased tamper circuit Red, blue, or green wires.
monitor circuit Orange and brown wires.
Note: For white and blue colors, see the optional color codes shown in
Figure 4.
Figure 5: Wiring for category 3
Note: For white and blue colors, see the optional color codes shown in Figure 4.
2 / 4 P/N 13924 • REV F • ISS 09SEP15
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