Lesson 3/Learning Event 2
Many terminals or connections are located around three front sides of the LVCT. We will start
with the terminals to the left of the ammeter. The first two terminals are used to connect the
external shunt to the LVCT. The terminals are polarity marked (+) and (-). The small red lead of
the shunt is connected to the positive (+) terminal and the black lead to the negative (-) terminal.
The top of the terminal is the head of a screw. It is knurled and rough so it will not slip in your
fingers. The screw is threaded into a long, smooth nut. The nut has a hole bored at right angles
to the threaded screw hole, and the test lead has a long pin on the meter end, which fits into this
hole. To make a connection, loosen the knurled screwhead by hand. Unscrew the knurled screw
until the test lead pin will slide through the hole. Then turn the knurled screw in until it is snug on
the pin. Always tighten by hand only. All of the test lead connections are connected in this
manner.
Just below the external shunt connections you will see two straps. Each strap can be connected to
two terminals. These straps are called links because they are a link of a circuit when they are
connected. We could say they are actually a switch because they can be used to open or close a
circuit. The upper link is used with the external shunt.
The next four terminals are used with the ammeter. The 6-gage test leads are connected to these
terminals. Three of the terminals are marked negative (-), and each of the three matches one of
the scales or ranges on the ammeter. The fourth terminal is marked COMMON and is therefore
the positive (+) connection for the three ranges. For example, if you wish to measure a current
flow of 20 to 30 amperes, you would connect the leads to the LVCT as follows: the red lead
positive to the common terminal and the black lead to the -50A (ampere) terminal. The other ends
of the leads would be connected in series with the circuit to be tested.
The next two terminals, located below the fine load control, are marked 24V and 12V respectively.
These terminals are used with the COMMON terminal when placing a load on a circuit with the
load bank. The 6-gage test leads are also used with these terminals, because heavy amperage (up to
100 amperes on 24-volt circuits) can be forced to flow through these terminals. The black lead is
connected to the common terminal when using the load bank. The red lead is then connected to
the 12- or 24-volt terminal, depending on which voltage circuit is being tested.
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