www.velocitydetection.com Doc: GLT-311-7-1 Issue: 001 Date: 28/10/2020
VDOT-U5015 Explosion Proof Smoke Detector
The smoke alarm relay has a single set of terminals and normally
open / normally closed contacts, and normally de-energized
operation.
The fault relay has a single set of terminals and normally open
contacts, and normally energized operation.
The auxiliary relay has a single set of terminals and normally open /
normally closed contacts, and normally de-energized operation.
IMPORTANT
The auxiliary relay functions as pre-alarm.
0 to 20 mA Output
The U5015 provides a 0 to 20 mA dc current for transmitting
detector status information to other devices. The circuit is wired in a
non-isolated configuration and can drive a maximum loop resistance
of 300 ohms from 12 to 17.9 Vdc, 500 ohms from 18 to 19.9 Vdc,
and 600 ohms from 20 to 30 Vdc. Table 1 defines the current levels
and corresponding detector status. The output is calibrated at the
factory, with no need for field calibration.
NOTE
The output of the 0 to 20 mA current loop is monitored by the fault
detection circuitry of the U5015. Therefore, an open circuit on the
loop will cause the fault relay to change state.
An alarm will normally over-ride a fault, unless the nature of the
fault impairs the ability of the detector to generate or maintain an
alarm output (i.e., loss of operating power).
INTEGRAL WIRING COMPARTMENT
All external wiring to the device is connected within the integral
junction box. The detector is furnished with a maximum of four
conduit entries, with either 3/4 inch NPT or M25 threads.
LED
An LED, located on the detector (see Figure 1), indicates normal
operation and notifies personnel of an alarm. Table 2 indicates the
condition of the LED for each status.
LATCHING
A detector configured for latching operation will remain in an alarm
state indefinitely, after an alarm occurs.
NON-LATCHING
A detector configured for non-latching operation will check the alarm
status of the detector once every 10 seconds. Once smoke falls below
the alarm threshold, the alarm annunciation will clear within 10
seconds.
IMPORTANT
The latching or non-latching configuration must be specified
during order placement.
It is
not
field configurable.
Only the alarm annunciation can be configured for latching
operation.
CONTINUOUS SELF-TEST
During normal operation, the detector performs the Self-Test
function automatically in the background once per second. During the
test, detection is not interrupted and no indication is given if the test
passed. If the test fails, a critical fault will occur. If degradation is
present and approaching critical levels, an advisory fault will occur.
MANUAL SELF-TEST
The Manual Self-Test function will immediately check the smoke
chamber optics for degradation. Once initiated, there will be a one
second delay before the result of the check is active. If there is a
failure, the LED will shut off immediately after the one second test
and a critical fault will occur. If the test passes, an alarm will be
annunciated while the LED remains active.
For a latching detector, the alarm will continue until power is cycled
to the unit. If the test passes, but there is degradation present and
approaching critical levels, an advisory fault will occur. For a non-
latching detector the alarm will clear after 10 seconds.
MAGNECTIC SWITCH
The magnetic switch is used to initiate the Manual Self-Test (see
Figure 3). Apply the magnet to the exterior housing and the LED will
light to indicate that the magnet is detected. The LED will remain lit
for at least one second during the test. After the initial delay, the
test status will be indicated as described in the "Manual Self-Test"
section.
