The NP-7310 Accelerometer which is attached to the VR-6100 Vibration Level Meter incorporates the shear shape piezoelectric accelerometer and preamplifier for 3-direction measurement. It is possible to extend between the accelerometer and vibration level meter up to 100 m by the incorporated preamplifier. Also, it is applicable to "JIS C0920 Degrees of protection provided by enclosures, grade 4" and "JIS F8007 Shipbuilding-Electrical equipments-General requirements for degrees of protection and inspection of enclosures ", so measurement is available in rainy weather, in water splashing place, in cloud of dust or powder dust place.

Accelerometer installation place

 

Select the measurement place of land surface depending on the measurement purpose such as nearby the measurement source or property line.

 

[Note]

When some place is specified as a measurement point, select the most suitable point for the measurement in the specified place. Also, if the specified place cannot be selected as a measurement point, select the measurement point in a place as close as possible to the specified place, and select several measurement points between the specified place and the measurement source and executes the measurement. Then, estimate the vibration level by interpolation method after obtaining the distance attenuation of the vibration level.

 

 

Select the measurement axis

 

In vibration measurement, the complicate vibration components are decomposed into measurement directions of 3 axes (horizontal direction: X axis and Y axis, vertical direction: Z axis), which are orthogonal with each other. Therefore, when the NP-7310 accelerometer for 3-direction measurement which is attached to the VR-6100 Vibration Level Meter is installed on the ground, the vertical direction is Z axis, and horizontal directions are X and Y axes. Two methods for determining the horizontal X and Y axes are available, one is based on measurement point and the other is based on vibration direction of vibration source. Determination method which is based on vibration direction is available when the vibration direction of the vibration source is stable and known value. However, in the general vibration pollution measurement (in Japan), the measurement direction is determined based on measurement point. Back and front direction from the measurement point to vibration source is X axis and right and left direction is Y axis. Also, the axis that is eligible for the vibration regulation law (in Japan) is only vertical direction axis.

[Note]
• The lateral sensitivity of the accelerometer is -20dB or less, so measurement axis difference around ±10 degrees between the X, Y axis and actual measurement axis (direction) does not affect to the measurement value. However, please prevent it from the extreme difference between the X, Y axis and measurement axis (direction) when install the accelerometer.

• When you view the NP-7310 Accelerometer from the above, the forward direction sign of the acceleration is X axis: from left to right, Y axis: from front to back. Also, the forward direction of the Z axis is upward from the ground.

 

 

Accelerometer installation

 

To correctly detect the ground surface vibration with the NP-7310 Accelerometer, it is necessary to detect vibration exactly the same as the ground surface vibration. If the installation surface is soft and difficult to install correctly, an error may occur to the measurement value. For this reason, please choose the flat hard surface such as concrete, asphalt, wood or hardstand ground to install the NP-7310 Accelerometer.

[Note]
• If you process the measurement on a soft ground such as grassland or dry fields by necessity, please remove grasses, pack down and strongly press the soil to install the unit.