Electrical Test Instruments PI-2500 & PI-5000
Section II - Detailed Description
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Copyright(C) 1994-2008 Electrical Test Instruments, LLC. All Rights Reserved
Page II-14
Illustration of PI-2500 Stab Plate Assembly:
AUX5000 Main Unit Circuitry
The AUX-5000 auxiliary unit connects to a 480 VAC supply and ground by
means of standard input jacks. Primary protection is provided by 200-amp fuses
F1 and F2. Main power is supplied to the output section by power contactors K1
and K2, which are energized when those in the PI2500 are turned on. There are
three solid state relays, which control power to the three sections of the output
transformer T1. They may be protected by fuses, and they are equipped with
snubbers to prevent spurious turn-on and latching of output.
Contactors K3 through K8 are operated for taps 4 through 9, and their coils are
driven by 24 VDC pulses from the Auxiliary Relay PCB. The primary of each trans-
former section is shorted when it is not needed; otherwise it is powered through
the SSR. Electrical interlocks on the contactors assure that both cannot be
pulled in at the same time.
The control connector to the PI2500 provide ACHI and ACLO power for the fan,
control signals for the contactors, initiate signal for the solid-state relays, inter-
locks, and sense leads for the output bus voltage from terminal 1 to 4.
The secondary windings of the transformer, consisting of two pairs of bus bars,
are bolted to the secondary bus bars of the mating PI-2500. The combined units
form a transformer which is nearly identical to the PI4000B.
The high strength and corrosion resistant stainless-steel output bolts should
rarely require replacement but may be serviced by simply removing the sixteen
screws on the phenolic output faceplate, and then removing one of four bolt
retainers. The standard hex head bolts may then be pushed through and re-
placed.
