Some of our users have expressed an interest in logging TIME.
Example applications include logging the time a freezer door is open and logging the time
a pump is running. In some cases users want to monitor a switch contact and log the time
the switch is turned ON and in other applications users want to log the time that three
phase or single phase power is switched ON to a device. These two cases have led to the
development of two different techniques for monitoring ON Time.
Monitoring the ON Time of a switch
We have developed a new probe type for the GP-HR and GP-MC loggers that monitors a switch
connected to any of the analog inputs. This switch is read every second and the total
number of seconds that the switch is ON in each logging period is recorded. As Point,
Maximum and Minimum readings have no meaning for this probe type, only Average readings
are available for logging.
Realtime readings show the current position of the switch.
The probe type is called ON Time Analog and became available
in Omnilog Version 1.38
Circuit diagrams for the connection of DPST and SPST switches to GP-HR and GP-MC loggers
are shown below under Technical Details.
Monitoring the ON Time of the Mains supply to a device
We have also created a new probe type that counts the number of
incoming mains power cycles on the Fast Pulse channel of the GP-HR and GP-MC (this is
therefore restricted to one channel per logger). We have developed a new sensor for this
job. The Alternating Current Monitor Probeset (ACM-PS) connects
directly to the mains supply and produces one pulse for every mains cycle. The idea here
is that each cycle of incoming power is counted and the result is divided by 50 (for a
50Hz system) or 60 (for a 60Hz system) to give an ON Time in seconds. The counter channels
can count up to 65535 so the maximum logging period for a 60Hz system is 18 minutes and
for a 50Hz system is 21 Minutes.
Realtime readings show the current amount of ON time in the current logging period.
The two probe types are called ON Time (50Hz) and On Time (60Hz) and became available in Omnilog Version 1.37
An Alternating Current Monitor circuit as required for ON Time (50Hz) and ON Time (60Hz)
time measurements is shown below under Technical Details.
Logging in Minutes or Hours of ON Time
All three ON Time probe types give readings in seconds but these can
be scaled to Minutes or Hours using the Select button in the Units and Scaling Box on the
Channel and Probe Setup Page in the Logger Control Window.
Viewing ON Time Results
The total ON Time can be viewed in the Statistics View and in the
Period Reports.
Technical
Details
DPST Switch ON Time Analog Input
Circuit for GP-HR
No additional components are required
Switch input can be connected to Channel1 (pin2), Channel2
(pin3) and/or Channel3 (pin4)
SPST Switch ON Time Input Circuit
for GP-HR
A pull up resistor is required for proper operation of this
circuit.
The value of the pull up resistor is dependent on the
length of cable between the switch and the logger. We recommend 1M ohm if the switch is 10
metres or less from the logger and 200 K ohms if the switch is 100m from the logger. If
the switch is being used with a long cable in an electrically noisy environment an RC
filter network across the switch may be required.
R1 = 200 K Ohms to 1M Ohm depending on distance from switch
to logger
Switch input can be connected to Channel1 (pin2), Channel2
(pin3) and/or Channel3 (pin4)
