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Logging ON Time Qs_rbbr.gif (1971 bytes)

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.

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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)


DPST_circuit_diagram.gif (3398 bytes)

 

 

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)

SPST_circuit_diagram.gif (3651 bytes)

 

DPST and SPST Switch ON Time Input Circuit for GP-MC

Switches can be connected to any of the eight analog inputs of the GP-MC
DPST switches require no other components
SPST switches require a pull up resistor

R1 = 200 K Ohms to 1M Ohm depending on distance from switch to logger

MC_DPST_circuit_diagram.gif (2399 bytes)MC_SPST_circuit_diagram.gif (2460 bytes)

 

 

Circuit  for ON Time (50Hz) and ON Time (60Hz)
for connection to GP-HR and GP-MC Fast Pulse Input

 

ACM-PS_Circuit_diagram.jpg (15984 bytes)