How To Perform Measurements; Measuring The Earth Voltage Of The Earthed Equipment Under Test - Velleman AVM52ERT Manual Del Usuario

3. Description
1 OK lamp
2 Function buttons
3 Ohm range buttons
4 Terminals
5 Scale plate
6 Battery compartment panel
4.

How to Perform Measurements

4.1 Preparation
A max. of 130 VDC is present across terminals E and C and P during measurement, or when you press the
SIMPLIFIED MEAS. button. The same max. voltage is present across terminals P and C when you press the
BATT.CHECK button. This means that you must never touch the terminals with your hands. Always press the
BATT.CHECK button after use so that all the range and function buttons are in the off position (buttons are NOT
depressed). Release the BATT.CHECK button.
Zero Adjustment
Check to see if the needle's starting position coincides with the position of the 0 on the Ω or V scale. Open the
battery cover and loosen/tighten the zero adjustment screw using a screwdriver. The cover can be opened 90°.
Cable Connection
Stick the earth bars P and C deep into the earth as shown in fig. 2 below.
Fig. 2
Drive the earthing pins into the ground at some 5 to 10 m of the earthed device. Connect the green cable with
terminal E, the yellow cable with terminal P, and the red one with terminal C. Make sure to place the auxiliary
earth bars in the moist part of the earth. Moisten the ground yourself if it is too sandy, rocky, or dry.
Where it is not possible to drive the auxiliary earth bars into the ground (for example on concrete), you can just
put the earth bars down, cover them with a cloth, and pour (preferably salt) water over them. This may allow
earth resistance measurements. Note that this does not work on an asphalt surface.
Keep the connection cables separate when connecting them. The result of the measurement is affected by the
induction of current or voltage if the cables are touching or entangled.
Measurement errors may occur if the resistance of the auxiliary earth bars exceeds 2 kΩ. Be careful, therefore,
when you put the auxiliary earth bars P1 and C1 in the damp earth. Also check the connection of the cables
with the terminals.
4.2

Measuring the Earth Voltage of the Earthed Equipment under Test

Press the AC V button. The earth voltage is indicated on the V scale. The earth resistance measurement may be
inaccurate if the earth voltage > 5 V. Turn off the power source of the tested device or reduce the earth voltage
to avoid this problem.
Note: The measurement is not influenced if the x1Ω, x10Ω, or x100Ω button is in the pressed-down position.
V. 02 – 27/05/2014
AVM52ERT
3
Fig. 1
©Velleman nv