LVM-250 Isolated Line Voltage Monitor

The LVM-250 is designed to measure 2-wire single phase 50/60Hz line voltage up to 250 VAC. It is used inconjunction with the eCNA automation to monitor the power line for voltage sags or a complete voltage loss. TheLVM-250 sends the measured RMS voltage to the eCNA via the LIN serial link. The eCNA monitors this voltage andbased on user defined parameters generate events that can be used to pause and re-start the SMS in the event ofan under voltage condition.

Figure 1: Voltage Monitor Connection

The voltage monitor board is powered by the LIN. It continuously sends the RMS voltage values to the eCNA viathe LIN serial communications.

Figure 2: Voltage Monitor Board

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LVM-250 Line Voltage Monitor Setup and Operation

The LVM-250 is calibrated at the factory. No further adjustments are required. Connect the LVM-250 to the eCNALIN and to the ‘line side’ of the UPS (Uninterruptible Power Supply) with the supplied cables (See Figure 1).

Power up the eCNA and navigate to the Local I/O Network status screen to view the Voltage Monitor status screen.The RMS Voltage is displayed on the Inputs section of the screen. The Inputs field displays the actual measuredline voltage. It is a running average of the measured RMS value. This value will help to determine the best Lowerand Upper Threshold values.

Now navigate to the LVM-250 Voltage Monitor setup screen. This screen is used to configure the LVM-250 VoltageMonitor control parameters.

Parameter Name Symbol Definition

Lower Voltage ThresholdTLV Establishes the low voltage trip point. Range = 0 to 250 volts

Upper Voltage ThresholdTUV Establishes the upper voltage okay point. Range = 0 to 250 volts

Voltage Low Event Hold-Off TimeVLHT Sets the delay from the line voltage not okay condition to the Line Voltage Low Event.

Range = 0:00 to 59:59 mm:ss

Voltage Low Window TimeVLWT Establishes a time period where the Voltage OK 1 Event can occur. Range = 0:00 to 59:59

mm:ss

Voltage OK Event Hold-Off TimeVOHT Sets the delay from the from the line voltage okay condition to the Line Voltage OK 1 and

OK 2 Events. Range = 0:00 to 59:59 mm:ss

Voltage Logging Period Sets the Voltage Logging interval. Range = 0:00 to 59:59 mm:ss. 0:00 disables logging.

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Events

These three Line Voltage events can be assigned to triggers.

TLLine Voltage Low - This event occurs when the line voltage goes below the ‘Lower Voltage Threshold’, V for a

V LHtime greater than the ‘Voltage Low Event Hold-Off Time’, T .

Line Voltage OK 1 - This event can only occur inside the ‘Voltage Low Window’. This event occurs when the linevoltage returns to the okay condition and remains okay for a time greater than the ‘Voltage OK Event Hold-Off

V O HTime’, T .

Line Voltage OK 2 - This event can only occur outside the ‘Voltage Low Window’. This event occurs when the linevoltage returns to the okay condition and remains okay for a time greater than the ‘Voltage OK Event Hold-Off

V O HTime’, T .

Figure 3

This diagram illustrates how the Line Voltage events can be generated. The red line represents the line voltage.

TL V LHWhen the voltage drops below the Lower Voltage Threshold, V , the Voltage Low Hold-off, T , and the Voltage

V LW V LHLow Window, T , timers start to tick. If the Voltage Low Hold-off timer, T , is allowed to expire, the Line

TUVoltage Low Event is generated. If the voltage goes above the Upper Voltage Threshold, V , before the Voltage

V LW VO HLow Window timer, T , expires, the Voltage Okay Hold-off timer, T , starts to tick. If this timer is allowed to

TUexpire, the Line Voltage OK 1 Event is generated. If the voltage goes above the Upper Voltage Threshold, V ,

V LW V O Hafter the Voltage Low Window timer, T , expires, the Voltage Okay Hold-off timer, T , starts to tick. If thistimer is allowed to expire, the Line Voltage OK 2 Event is generated.

VLH TU1. The Voltage Low Hold-off timer, T , is reset if the voltage goes above the Upper Voltage Threshold, V andthe Line Voltage Low event will not be generated.

V O H TL2. The Voltage Okay Hold-off timer, T , is reset if the voltage falls below the Lower Voltage Threshold, V , andthe Line Voltage OK 1 or the Line Voltage OK 2 event will not be generated.

V LW TU3. The Voltage Low Window timer, T , is reset if the voltage goes above the Upper Voltage Threshold, V .

Application

The Line Voltage Low Event can be used to automatically and systematically shut down the equipmentand notify theatre personnel of a power problem. The Line Voltage OK 1 Event can be used toautomatically recover from a low voltage condition, such as resuming the movie. The Line Voltage OK2 Event can be used to take appropriate action when the voltage is restored. The following twoexamples demonstrate how the voltage monitor can be used. The macros and triggers can be addedto an existing application.

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Example 1

In this example, a 10 second timer starts when the line voltage drops below 185 volts. If the voltagegoes above 190 volts before the timer reaches 10 seconds, the timer is reset and the SMS willcontinue to play. If the timer expires, the SMS will be paused.

LVM-250 Settings:

Lower Voltage Threshold = 185 VoltsUpper Voltage Threshold = 190 VoltsVoltage Low Event Hold-Off Time = 10 secondsVoltage Low Window Time = 0 secondsVoltage OK Event Hold-Off Time = 0 seconds

Trigger Assignments:

The following trigger assignments are used in this example.

Name Controlled by Calls MacroLine Fault Line Voltage Low 9: SMS Pause/Stop

Macro:

The SMS Pause/Stop macro (macro 9) is called when the Line Voltage Low event pauses the SMS.

9: SMS Pause/StopProjector Digital 1 Vid Off 00:00 Pause/Stop the SMS

There is a caveat to the example above. If the power comes and goes after the SMS has been paused,the RPT,EVT,0,DV1OFF,... message may be sent again and again to the SMS. This shouldn’t be aproblem, but it can be prevented by using a control flag and the ‘Exit If’ instruction.

In the example below, the Aux Out 16 output control flag is used as the Voltage Monitoring (VM)control flag. If the voltage returns to the okay condition, the VM flag is set. When this flag is set (On),the Digital 1 Vid Off instruction is skipped and the RPT,EVT,0,DV1OFF,... message is not sent again.The flag must be cleared so the eCNA is ready to sense the next power outage. This should happen ona start or resume by setting Aux Out 16 = Off with an output command or a macro.

New Trigger Assignment:

Name Controlled by Calls MacroSet VM Flag Line Voltage OK 2 10: Set VM Flag

Macros:

The SMS Pause/Stop macro is modified with the Exit If instruction. The macro is called when the LineVoltage Low event pauses the SMS only if the Voltage Monitoring (VM) flag is cleared.

9: SMS Pause/StopExit If Out 16 On 00:00Projector Digital 1 Vid Off 00:00 Pause/Stop the SMS

The Set VM Flag macro sets the Voltage Monitoring (VM) flag to prevent an unwanted pause message.

10: Set VM FlagExit If Out 16 On 00:00 Set VM Flag

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Example 2

In this example, a 10 second timer starts when the line voltage drops below 185 volts. If the voltagegoes above 185 volts before the timer reaches 10 seconds, the timer is reset and the SMS willcontinue to play. If the timer expires, the SMS will be paused. If the voltage is restored before 1minute, the SMS is restarted if the voltage is okay for 5 seconds. If the voltage is restored after 1minute, the SMS remains paused.

The Aux Out 16 output control flag is used as the Voltage Monitoring (VM) control flag. If the voltagereturns to the okay condition after 1 minute, the VM flag is set. This prevents the SMS from restartingif the voltage is restored. The flag must be cleared so the eCNA is ready to sense the next poweroutage. This should happen on a start or resume by setting Aux Out 16 = Off with an output commandor a macro.

LVM-250 Settings:

Lower Voltage Threshold = 185 VoltsUpper Voltage Threshold = 190 VoltsVoltage Low Event Hold-Off Time = 10 secondsVoltage Low Window Time = 1 minuteVoltage OK Event Hold-Off Time = 5 seconds

Trigger Assignments:

The following trigger assignments are used in this example.

Name Controlled by Calls MacroLine Fault Line Voltage Low 9: SMS Pause/StopSet VM Flag Line Voltage OK 2 10: Set VM FlagLine Okay Line Voltage OK 1 11: SMS Strt/Resum

Macros:

The SMS Pause/Stop macro (macro 9) is called when the Line Voltage Low event pauses the SMS onlyif the Voltage Monitoring (VM) flag is cleared.

9: SMS Pause/StopExit If Out 16 On 00:00Projector Digital 1 Vid Off 00:00 Pause/Stop the SMS

The Set VM Flag macro (macro 10) sets the Voltage Monitoring (VM) flag.

10: Set VM FlagExit If Out 16 On 00:00 Set VM Flag

The SMS Strt/Resum macro (macro 11) resumes the SMS only if the Voltage Monitoring (VM) flag iscleared.

11: SMS Strt/ResumExit If Out 16 On 00:00Projector Digital 1 Vid On 00:00 Resume the SMSAux Out 16 Off 00:00 Clear the VM flag

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Voltage Logging

The eCNA-10 can log line voltage data collected from the LVM-250 Line Voltage Monitor. The VoltHiLoEvent (#105) contains the highest and lowest line voltage values collected since the last loggedVoltHiLo event. The Voltage Logging Period parameter on the LVM-250 Voltage Monitor setup screensets the logging interval. The range is 0:00 to 59:59 in minutes and seconds. 0:00 suppresses loggingof the event.

Logging the line voltage can be helpful in detecting problems, such as voltage sags, surges, brown-outs or total failure of utility power that can cause problems with or even damage the cinemaequipment.

Just for fun, the following graph was created with both high and low line voltage plotted over a 15minute period. The voltage was collected every second. The graph was created in an Excel Worksheetwith imported VoltHiLo Event records.

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