1-10
1.5 ELECTRICAL SYSTEM
1.5.1 AC Power Distribution
Reference Drawings 91S25906 thru 91S25912
The 2500 requires a 120 VAC/60Hz or 100 VAC/50Hz, single phase, 15 amp primary power
source (240 VAC/60Hz or 220 VAC/50Hz, single phase, 10 amp primary power source for
HV power option). From CBS1, primary power is applied to TB1 terminals 1 & 2. From
TB1 the primary power is distributed to the 24 VAC step-down transformer (TR1), the
refrigeration compressor (C1) through SSR8, the presaturator heaters (H1 & H2) through
SSR9, the fluid heater (H3) through SSR10, the fluid pump (FP1) through SSR6, and the
console fan (CF1) through SSR7.
1.5.2 Power Supply 24 VAC
Reference Drawing 91S25906
The 24 VAC Step-down Transformer (TR1) provides 24 VAC power for all solenoid valves,
as well as power input for the STD Power Supply Card (STD-PS) located in the computer
card cage.
1.5.3 Power Supply (STD-PS)
Reference Drawing 91S25906
The Power Supply Card (STD-PS) is a multiple isolated output voltage source providing
power to the STD bus computer system, as well as the flow transducer, pressure transducers,
solid state relay board (SSRB), terminal interface board (TIB), stepper motor drives (SMD-1
& SMD-2), the liquid lever monitor boards (LL1 & LL2), and the LCD backlight inverter
circuit.
The Power Supply Card receives power from the 24 VAC step-down transformer (TR1), then
rectifies and filters this into +24 VDC unregulated. The unreg24 VDC feeds an
onboard DC to DC converter which provides the reg5 VDC and ±12 VDC for the
STD bus and other equipment. The unreg24 VDC also powers the stepper motor
drivers (SMD-1 & SMD-2). Note that the +24 VDC Return is electrically isolated from the
+5 VDC and ±12 VDC Common.
Each item listed below utilizes the power from the Power Supply Card (STD-PS) for its
particular voltage requirements.
Voltage
Transducer
+24 VDC
Stepper motor drivers (SMD-1 & SMD-2)
+12 VDC
Mass flow transducer (T1)
+12 VDC
50 PSIA transducer (T2)
+12 VDC
150 PSIA transducer (T3)
±12 VDC
A/D board (STD-A/D)
-12 VDC
LCD backlight
+5 VDC
All STD bus cards (STD-CPU,STD-LCD,STD-MEM,STD-A/D)
+5 VDC
Solid state relay board (SSRB)
+5 VDC
Terminal interface board (TIB)
+5 VDC
Liquid level boards (LL1 & LL2)
