Vanguard MCCB-250 - Manual (Page 12)

MCCB-250 USER’S MANUAL REV 2
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2.4 MCCB-250 Timer
The MCCB-250’s built-in time/cycle counter can be used to time events in milliseconds and
cycles. The elapsed time is displayed on the LCD screen along with the test current after a test is
completed. A typical test results screen is shown in Figure 2. The timer is turned on when the
ON+TMR mode is selected.
Figure 2. Typical MCCB-250 Test Results Screen
2.5 External Current Input
The MCCB-250’s [EXT CURRENT] input serves as a built-in ampere meter
that can be used to monitor an AC current. This current is isolated, and the
maximum input current is 10 amperes. A typical application for this feature is to
measure a current transformer (CT) current ratio. The MCCB-250 can be used to
output a current to the CT primary input. The CT secondary output is then
connected to the MCCB-250’s
[EXT CURRENT] input. Both the MCCB-250
output current and the CT secondary current are displayed on the LCD screen
(see Figure 2). The user can use the displayed values to quickly calculate the CT
current ratio manually.
2.6 LCD Contrast Control
To change the LCD screen’s contrast, press and hold the [RIGHT ARROW] key next to the
LCD screen (item 14 in Figure 1). The screen contrast will increase until it reaches the darkest
setting. Then it will return to the lightest setting and begin increasing the contrast again.
Release the
[RIGHT ARROW]
key when the desired contrast level has been reached.
NOTE
The MCCB-250 will store the current LCD setting in non-volatile memory.