75
It shall be possible to manually start the self-test:
• In Navigator display, this test shall be located at Service
Test
AC.DT
EC.TS.
• Running the test shall require setting Service
Test
TEST=ON
The test shall also automatically run based on EC.DY
(T24_ECDY) and EC.TM (T24_ECTM):
• If conditions are acceptable to run the self-test (see
below), the test shall be automatically started on the con-
figured day EC.DY (T24_ECDY) at the configured time
EC.TM (T24_ECTM).
• If conditions are not acceptable to run the self-test, it
shall be re-scheduled for 24 hours later.
The economizer self-test shall only be allowed run if all of the
following conditions are valid:
1. The economizer is enabled
2. No actuators are detected as stuck
3. No actuators are detect as unavailable
4. RCB1 is properly communicating
5. The unit not down due to failure (A152)
6. The supply fan VFD is not in bypass mode (if unit has
this option)
7. If configured for building pressure, the unit has an return
fan VFD and the fan is not in bypass mode
In addition to the above conditions, the economizer self-test
shall not be automatically run if any of the following condi-
tions are valid:
1. Unit not in OFF or VENT mode.
The Test screen should be similiar to the following:
EC.TR ON
EC.DT WAITING
S.VFD 20.0 %
TORQ 17.5 %
ECN.P 20 %
EC2.P 0 %
EC3.P 0 %
EC.ST RUNNING
Setting EC.TS=ON shall perform the following:
1. Command all actuators and dampers to the closed posi-
tion.
2. Run the fan at T24SFSPD for T24ACMRT minutes and
take a baseline torque (VFD1TMAV) measurement. With
the dampers closed, there will be the least amount of air-
flow, and therefore the least amount of motor torque.
3. Modulate a single actuator/damper assembly open to
T24ACOPN. This will increase the airflow.
4. Let the motor run for one minute. If the torque has in-
creased by T24VFDPC % over the baseline measurement
from Step 2, the current torque is set as the new baseline
measurement and proceed to Step 5. If the torque has not
increased by T24VFDPC % continue to run the fan for a
total of T24ACMRT minutes. If, after T24ACMRT min-
utes total, the torque has not increased by T24VFDPC %
over the Step 2 baseline measurement, a fault is logged,
and the test is ended.
5. Modulate the actuator/damper assembly closed.
6. Let the motor run for one minute. If the torque has de-
creased by T24VFDPC % over the baseline measurement
from Step 4, the current torque is set as the new baseline
measurement and proceed to Step 7. If the torque has not
decreased by T24VFDPC % continue to run the fan for a
total of T24ACMRT minutes. If, after T24ACMRT min-
utes total, the torque has not decreased by T24VFDPC %
below the Step 4 baseline measurement, a fault is logged,
and the test is ended.
7. Repeat Steps 1-5 for additional actuator/damper assem-
blies.
8. Command actuators/dampers to "normal" positions.
If the torque increases and decreases properly,
EC.ST="PASS", otherwise EC.ST="FAIL".
If EC.ST is set to pass, any existing "damper not modulat-
ing" alert shall be automatically cleared.
If EC.ST is set to fail, the "damper not modulating" alert
shall be logged.
If at any point in the test the fan does not reach the com-
mand speed or an actuator does not reach the command posi-
tion within five minutes, the test shall be stopped and the status
set to "NOT RUN."
FDD CONFIGURATIONS
Log Title 24 Faults (LOG.F) — Enables Title 24 detection
and logging of mechanically disconnected actuator faults.
T24 Econ Move Detect
(EC.MD) — Detects the amount of
change required in the reported position before economizer is
detected as moving.
T24 Econ Move SAT Test
(EC.ST) — The minimum
amount the economizer must move in order to trigger the test
for a change in SAT. The economizer must move at least
EC.ST % before the control will attempt to determine whether
the actuator is mechanically disconnected.
T24 Econ Move SAT Change
(S.CHG) — The minimum
amount (in degrees F) SAT is expected to change based on
economizer position change of EC.ST.
T24 Econ RAT-OAT Diff
(E.SOD) — The minimum amount
(in degrees F) between RAT (if available) or SAT (with econo-
mizer closed and fan on) and OAT to perform mechanically
disconnected actuator testing.
T24 Heat/Cool End Delay
(E.CHD) — The amount of time
(in minutes) to wait before mechanical cooling or heating has
ended before testing for mechanically disconnected actuator.
This is to allow SAT to stabilize at conclusion of mechanical
cooling or heating.
T24 Test Minimum Position
(ET.MN) — The minimum po-
sition below which tests for a mechanically disconnected actu-
ator will not be performed. For example, if the actuator moves
entirely within the range 0 to ET.MN a determination of
whether the actuator is mechanically disconnected will not be
made. This is due to the fact that at the extreme ends of the ac-
tuator movement, a change in position may not result in a de-
tectable change in temperature. When the actuator stops in the
range 0 to 2% (the actuator is considered to be closed), a test
shall be performed where SAT is expected to be approximately
equal to RAT. If SAT is not determined to be approximately
equal to RAT, a “damper not modulating” alert shall be logged.
T24 Test Maximum Position
(ET.MX) — The maximum po-
sition above which tests for a mechanically disconnected actua-
tor will not be performed. For example, if the actuator moves
entirely within the range ET.MX to 100 a determination of
whether the actuator is mechanically disconnected will not be
made. This is due to the fact that at the extreme ends of the ac-
tuator movement, a change in position may not result in a de-
tectable change in temperature. When the actuator stops in the
range 98 to 100% (the actuator is considered to be open), a test
shall be performed where SAT is expected to be approximately
equal to OAT. If SAT is not determined to be approximately
equal to OAT, a “damper not modulating” alert shall be logged.
SAT Settling Time
(SAT.T) — The amount of time (in sec-
onds) the economizer reported position must remain un-
changed (± EC.MD) before the control will attempt to detect a
mechanically disconnected actuator. This is to allow SAT to
stabilize at the current economizer position. This configuration
sets the settling time of the supply-air temperature (SAT). This
typically tells the control how long to wait after a stage change
To Next Page
Loading...
