Vanguard CT-7500 - Manual (Page 19)

MODEL CT-7500 OPERATING INSTRUCTIONS
Rev 2 Jan 2001
13
8.0 TEST HOOKUP CONNECTIONS
8.1 Contact Cable Hookup
A typical contact cable connection to a circuit breaker is shown in Figure 8-1.
NOTE
It is advisable to ground one side of the contacts for most testing. If a breaker is floating
(i.e., ungrounded), ensure contact-channel inputs are protected against static discharge.
A typical series contact connection is shown in Figure 8-2.
8.2 Initiate Cable Hookup
A CT-7500 will trip or close breakers with a solid-state device, which will operate on any ac or
dc control voltage from 10 to 300 volts. Both the trip and close circuits are protected by 3-ampere
fuses.
A typical dc trip and dc close control circuit test hookup is shown in Figure 8-3.
A typical dc trip and ac close control circuit is shown in Figure 8-4.
8.3 Analog Voltage Monitor Hookup
The analog voltage input (V1) lets users monitor a breaker's dc-control voltage during
operation. The analog voltage input (V1) will record the norminal dc voltage (at no load) and the
minimum dc voltage (while the Trip or Close coil is energized).
Nominal and minimum voltage readings will print on a tabulated report. Analog waveform will
also plot in a graphic report. This lets the user see the breaker's dc control voltage "dip" under
load. Problems, such as a poor connection or an excessive voltage drop, during operation can
thus be easily detected.
A typical voltage monitoring hook up is shown on Figure 8.5.
NOTE
Maximum voltage recorded is 255 Vdc.
8.4 Digital Voltage Monitor Hookup
The Digital V2 voltage input channel lets users monitor the voltage ON/OFF state. The voltage
ON/OFF state will be plotted on the graphic report. A typical hook up is shown on Figure 8.5.
8.5 External Trigger Input
External trigger mode lets a user start a recording when the CT-7500 senses a voltage. A
typical application for this external trigger mode is to time a circuit breaker in a close operation and
to start timing only when the close coil is energized (bypassing the 52X relay delay time).
Since the 52X relay carries the close coil current, the user wants to connect the CT-7500’s initiate
cable to the close terminal (figure 8-4). The CT-7500 will energize the 52X relay to start the close
operation. The CT-7500 then will start the timing when it senses the voltage across the closing
coil. See Figure 8.6 for a typical test hookup.
Another application (for external trigger) is to start timing the breaker when the user trips or closes
the breaker remotely.