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Entek IRD 6687 Protection Monitor
6687 Monitor
Testing Calibration and Relays
To test the monitor’s calibration, you connect a known signal to the backplane of the
monitor and read the signal from the display on the front of the monitor. You can test the
relays by changing the input signal to cause a relay to change state.
Signal Inputs for Testing
When testing any of the 6600 protection monitors, you must use the correct input signal.
Please use the following guidelines when setting the input signal:
z
Note that the sensitivity is given in mV DC. Make sure your multimeter is set to read
voltage in volts DC.
z
You will need the following information to calculate the input signal. The menu options
are from the RANGES (page 21) and TX OK submenus (page 22).
Full scale LO value
(FS LO 1)
________________
Full scale HI value
(FS HI 1)
________________
Voltage at FS HI
________________
Voltage at FS LO
________________
TX Voltage low
(TX LO 1)
________________
TX Voltage high
(TX HI 1)
________________
Zero position
________________
The “zero position” is the cold case position. This calibration procedure assumes that
you set TX ZRO to read 0 mil on the monitor (see “Setting the Display Scale and Zero
Position” on page 24).
To obtain the voltage at FS LO, connect a voltmeter to the input and take readings when
the case is at the cold position. To obtain the voltage at FS HI, place a spacer between
the case and the plunger of the LVTD. The spacer should be the same length as the
maximum change in case expansion (1000 mils for this example).
Transducer
Sensitivity
LVDT (model 15383)
9.72 mV/ mil (0.374 mV/µm)
