Dulas Solar VC150, Handbook

Page: 47 / 156

47
2.3
MEASURING CURRENTS
2.3.1 Use a millimeter or DC ammeter to measure current in the following manner:
1. Set the millimeter to measure current. The setting on the selection knob may
be labeled “current”, ”amperes”, ”amps” or just “A”.
2. Set the range so that it included the current that you expect to measure. If you
expect current to be about 5A,set the range to 0-10 A.
3. Plug the meter leads into the correct sockets in the meter. Make sure that the
negative (black or -) lead goes into the negative (or “common”) socket and
that the positive (red or +) leads goes into the current (A) socket.
4. Make sure that the meter is switched ON and that it has batteries inside.
Some types of meter are switched ON automatically when you turn the
measurement selection knob.
5. If the meter is an analogue meter as shown above make sure that the needle
points to 0 amps when the metal tips of thermometer leads are not touching
anything. If the needle does not point at 0 amps, adjust zero setting screw
until it does. Look at the scale with it straight in front of you so that you can
read it accurately. Do not look from the angle.
6. Switch OFF the circuit. Disconnect at one terminal the wire through which you
want to measure the current.
7. If you have disconnected the positive wire, connect it to the black (common)
meter lead. If you disconnected the negative wire, connect it to the red lead.
To make the connection use a crocodile clip to hold the lead and the wire
together.
8. Touch the metal tip of the other metal lead to the terminal from which you
disconnected the wire.
9. Switch ON the circuit. Be careful not to make a short-circuit between the
terminals by accidentally touching both terminals.
10. Note down the reading. Make sure you read from the correct range on the
Scale if the meter is an analogue ammeter.