Type C Track Circuit Uninterruptable Power Supply

Instruction
& Maintenance
Model CXP-3
Safetran Systems
Type C Track Circuit
Uninterruptable Power Supply

Instruction & Maintenance
Type C Track Circuit
Uninterruptable Power Supply
Introduction..........................................................................................................................2
Specifications.......................................................................................................................3
Installation............................................................................................................................4
TroubleShooting...................................................................................................................5
Replacement Parts...............................................................................................................6
Schematic.............................................................................................................................7
Notes....................................................................................................................................8
I & M 010350-13
New 2/95
Contents

Model CXP-3 Type C Track Circuit
Uninterruptable Power Supply
The model CXP-3 Type C Track Circuit Uninterruptable Power Supply (UPS) employs a
track feed transformer, power transfer relay, and standby inverter in a single housing.
The CXP-3 acts as a track feed transformer when the circuit is operated with 115 VAC
input power. In the event of AC power interruption, the CXP-3 converts standby battery
power to an output voltage of the same RMS value as the output under normal
operating conditions. The output voltage is proportional to the input voltage.
The inverter runs in the standby mode. It is turned on by an internal power transfer
relay in the event of the AC input power being lost. The inverter uses rugged MOSFET
power transistors with the highest available current rating. The operating frequency is
kept to within 1 Hz of nominal under any voltage, load, or temperature condition. Surge
protection for the solid state circuitry consists of seven separate stages, including
MOV's, Transorbs, Zeners, inductors and capacitors. All electronics are isolated from
the chassis, giving a 3000 VAC breakdown voltage.
The model CXP-3 is capable of operating up to 4 track circuits through 4 separate
outputs of 6.3 VAC and 3.5 amperes each. Inputs are provided for both 115 VAC
commercial power and 12 VDC standby battery power. The inverter unit is of a high
efficiency design to maximize run time on the battery in the event of power failure.
The model CXP-3 measures 8 inches in height, 5-1/4 inches in width, 9 inches in depth
and weighs 15 pounds. It can be mounted on a standby relay rack, backboard, or shelf.
2

Electrical:
Specifications
Input Current: no load .25A
half load 3.5A
full load 6.5A
Input Voltage: 12.8V
Output Voltage: no load 7.3VAC
half load 6.2VAC
full load 5.6VAC
Output Current: 3.5A Maximum
Efficiency: 1/4 load 70%
half load 89%
Output Wave: Square
Frequency: no load 60.0Hz
half load 60.0Hz
full load 60.0Hz
Physical:
Ambient
Temperature: maximum 159.8° F (71° C)
Dimensions: height 9 inches
width 5-1/4 inches Exclusive of mounting tabs or terminals
depth 9 inches
3

Installation
1. The Model CXP-3 should be rack, wall or shelf mounted within a dry, well ventilated
housing. Four #10 wood screws are provided.
2. Connect the battery to the input terminals being careful to observe the proper polarity.
A buzzing sound should be audible indicating that the inverter is working properly.
Leads between the battery and power supply should be No.9 AWG at minimum and
should be as short as practicable.
3. Measure the AC output voltage across the output terminals. The value read should be
in accordance with the no load specification value. Note that the output voltage will vary
proportionally with the input voltage applied.
4. Connect the load to the output terminals and again measure the AC voltage to make
certain that it is satisfactory.
5. With power off, connect commercial AC power to the CXP-3 unit between terminals BX
and CX as labeled on the cover. Once the power is applied, the internal power transfer
relay will pick up, removing power supplied to the inverter and therefore eliminating the
buzzing sound created by the inverter.
6. Again measure the AC output voltage across the output terminals to make certain that it
is satisfactory.
7. Surge protection for track circuits and AC line should be provided in accordance with
Railroad Standard Practice. See application drawing below for recommended surge
protection.
MODEL 485-28
CLEARVIEW®
LIGHTENING ARRESTER
(#022485-28X)
1T 2T 3T
1TR 2TR 3TR
DC MODEL CXP-3 POWER SUPPLY
115 VAC/12 VDC INPUT
AC
MODEL SP19-2A
SURGE PROTECTION NETWORK
(#010806-3AX)
EQUIPPED WITH A MODEL 700-1
HEAVY DUTY EQUALIZER
(#022700-1X)
4
MODEL SP20-2A
SURGE PROTECTION NETWORK
(#010807-6AX)
EQUIPPED WITH A MODEL 701-1
AC LINE PROTECTOR
(#022701-1X)
MODEL 700-1
HEAVY DUTY EQUALIZER
(#022700-1X)

Trouble Shooting
Trouble encountered with the CXP-3 will generally be contained within the internal solid
state inverter as a result of low or no output. The following causes may be responsible and
steps are outlined to isolate the cause.
1. Low output or loss of output
Check the input to see that it is close to its nominal value. The output AC voltage will
vary directly with the input DC voltage. If a low input voltage is responsible, this
condition must be corrected. Considerable drop in voltage may occur in the leads
between the battery bus and inverter under heavy load conditions. It is for this reason
that heavy gauge wire and short leads are recommended on the input.
2. Excessive or short circuited load
If this cause is suspected, remove the load and measure the no load voltage of this
output. Check to be sure the fuses have not blown. Always replace with fuses of the
same type and rating. This reading should be consistent with the no load specification
values. If the no load conditions are proper, connect the load through an AC ammeter
to see if the drain is excessive. A load current greater than 3.5A per output indicates a
faulty or excessive load. Note that at full load the input current requirement may be as
much as 10.0A. The battery must be kept well charged to insure that input voltage will
be maintained with this load. With a short circuit or very high current load, either fuse
can be blown.
5

Model CXP-3 Type C Track Circuit
Uninterruptable Power Supply
Replacement Parts
To Order: Specify Description and Part Number
Part Qty.
Description
No. Req'd
Schematic Power Supply CXP-3 010350-10 1
Side Wrap CXP-3 Power Supply 010350-9 1
Top Wrap Inverter 010247-9 1
Transformer 88 VA 010247-88 1
Choke Coil #11 Wire 10" Leads 010802-7L 1
Insulating Shield 1-7/16 W/1 Slot 023408-14 2
Insulating Cap 023408-13 2
Fuse Holder 010019-9 2
Fuse 3AG 15 Amp 010350-8 1
Fuse 3AG 1.5 Amp 010350-6 1
Varistor 24 Volt 010900-51 4
Varistor 150 Volt 010900-45 1
PC Board Assembly CXP-3 w/Lead 010247-10X1 1
Wire
Transorb Assembly Unidirectional 010247-16X 1
Relay 120VAC P&B #PM17AY 010350-11 1
Screw Wood RD #10 x 3/4 Stl Zinc 5730-RSC 4
6

Schematic
7

Notes
8

Safetran Systems
Safetran Systems Corporation
4650 Main Street N.E.
Minneapolis, MN 55421
(612) 572-0466