2.14.2
Relays
Relays shall be
two-pole, double-throw (DPDT) with a 10-ampere resistive
rating at [120]
[24] Vac, and shall have an enclosed coil. Provide with a
light indicator
which is lit when the coil is energized and is not lit when
the coil is not
energized.
2.14.3
Time-Delay Relays
Time-delay relays shall be DPDT with octal connectors and dust covers.
The
adjustable timing range shall be [0 to 3 minutes] [_____].
2.14.4
Time Clocks
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NOTE: Indicate time clock to automatically index to
day or night thermostats; control system shall
function on Saturday and Sunday as specified for
night cooling and heating. The second clock circuit
of the same clock that controls HVAC air delivery
system timing shall be used to maintain outside air
dampers closed from beginning of night period
through the morning warm-up period.
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Time clocks shall be a 24-hour, 365-day programmable timing device with two
independently timed circuits. Clocks shall have a manual scheduling keypad
and alphanumeric display of timing parameters. Timing parameters shall
include Gregorian calendar date for month, day and day-of-month indication;
and 24-hour time-of-day display, with one-minute resolution for programming
the ON and OFF times for each circuit. Circuits shall have programmable
timed override from 1 to 99 minutes. Clocks shall have capacity for
programming four ON events and four OFF events for each circuit.
Programmed events shall be assignable to a 365-day schedule. Clocks shall
have automatic standard time and daylight saving time adjustments, keyed to
input of appropriate dates. Provide clocks with 4-day battery backup.
2.14.5
Override Timer
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NOTE: Mechanical override timer, when activated,
shall bypass the time clock and activate the day
heating or cooling and ventilation controls for
assigned units. Upon expiration of timer operation,
the control system shall return to normal mode.
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Override timers shall be manually set, mechanically driven timers, or
electronic timers, without a "hold" feature. Time intervals shall be
selectable for up to 12 hours of operation and shall expire unless reset.
2.14.6
Current-to-Pneumatic (IP) Transducers
Transducers shall be two-wire transmitters which convert an input signal to
21 to 103 kPa (gage) or 103 to 21 kPa (gage) 3 to 15 psig or 15 to 3 psig
pneumatic output, with a conversion accuracy of plus or minus 2 percent of
full scale, including linearity and hysteresis. Air consumption shall not
be greater than 0.12 L/s 0.25 scfm.
SECTION 15901N
Page 36
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