The purpose of this document is to provide detailed explanation of multi-output switch
mode power supply operation and wiring. This information will help with the installation
and troubleshooting of a supply in the field. This example is for the UIC 30109000 (LH
or Deltron) Power Supply having four outputs. Concepts in this document may lend
themselves to other power supply applications.
Deltron Model SQ175-1233
Output Voltage Current
V1 5 VDC 20 A
V2 12 VDC 5 A
V3 15 VDC 4A
V4 15 VDC 1.5 A
LH Model TM34-12Y33Output Voltage Current
V1 5 VDC 20 A
V2 12 VDC 5.0 A
V3 15 VDC 4.0A
V4 15 VDC 1.5 A
Total Power
It is important to note all current ratings are individual maximums and in no way could
the power supply deliver the total power of 242.5 W if all outputs were loaded to their
maximum output capacities. The Deltron supply and the LH supply are both rated for
175W continuous output power. Exceeding this limit will cause the supply to overheat
and result in damage.
Derating
Derating a supply is a process of discounting the power supply's output capacity due to
reduced airflow or poor heatsinking. If the supply is operated in a cabinet with poor or
reduced airflow, the power supply ratings must be derated to account for the heat
buildup over time. A supply may function well initially but begin to fail after the circuit
temperature rises above 85 degrees Celsius. Make certain the chassis cooling fan is
functioning properly as part of a preventative maintenance program on the machine. If
the cooling fan fails, make certain to replace it with a fan of equal or better airflow
ratings.
Connections
Warning! The following information is for discussion purposes only, wiring must be
performed by a qualified electrician or electronics technician. Do not attempt to modify
or make wiring connections unless you are qualified to do so. Machine power to the
entire machine must be off and mechanically locked out with a padlock before
attempting to install, remove or correct wiring.
Power Supply Terminals
AC AC Gnd -S1 -V1 -V1 +S1 +V2 -V2 +V3 -V3 +V4 -V4 RS
Input Power
The power input connections (AC) terminals must be connected to fuse or circuit
breaker protected AC source. Most UIC installations use 120 VAC, in some cases 240
VAC may be used. Supplies must be modified (jumpers) to function with 240 VAC - Do
not attempt to operate a 120 VAC configured supply in a machine installation using 240
VAC!
Ground
Make certain the ground (Gnd) connection is wired to both an earth ground wire and to
a chassis ground jumper wire for additional safety.
V1
The first output on the supply is the V1 output. This output is 5 VDC and supplied
power to all of the I/O boards located in the I/O box of the machine. This does not
supply the controller (ex. 8221 or 8222) of the machine, the controller has its own
supply. The V1 output has a sense feature that allows wiring sense wires from the I/O
box backplane back to the V1 output circuit to automatically compensate for any voltage
drop due to the high current through the wiring and bus plane. Sense wires, when
employed are typically a light gauge wire (20 AWG) compared to the heavier gauge for
the 5 VDC bus wiring.
Sense jumpers must be installed across the v1- and s1- terminals and the v1+ and s1+
terminals if no sense wires are present on the machine. Sense wires are used to bring
the +5 VDC signal level back to the supply to account for a voltage drop in the bus
wires. UIC may or may not employ the sense wiring on all machines. When the sense
wires are present, the sense jumpers may be removed. Minimal loading of V1 is
necessary for the remaining outputs of the supply to function. Do not attempt to operate
the supply with V1 open or loaded less than 5 Amps.
The second output on the supply is the 12 VDC output. This output is typically used for
peripheral I/O boards utilized on the machine and in some cases may be wired to the
I/O box.
V3 and V4
V3 and V4 provide the -15 and +15 VDC to the machine I/O box. These sources are
primarily used by the servo system components such as DAC Feedback and Servo
Amp cards. In order for the V3 and V4 outputs to provide the bipolar output, a jumper or
wire in the harness should tie the V3 and V4 supplies together at a common point.
Either the V3+ is tied to the V4- or the V4+ is tied to the V3- terminal to create a -15V
and +15V supply with a common at the V3+ and V4- terminal or the V4+ and V3-
terminals respectively. It is important to note the current rating on the V3 supply is 4
Amps Verses the V4 supply is only 1.5 Amps. If the +15 VDC loading on the machine is
above 1.5 Amps, the second wiring option would be the best option. It is important to
consult the machine-wiring diagram for the correct wiring of these outputs. The
common tie may occur at the machine I/O box and wiring the V3 and V4 may not
involve any jumpers at the power supply terminal strip.
RS
No connection to the RS terminal is used, leave it open.
Troubleshooting
The most important consideration is that all outputs are connected to the machine. V2,
V3, V4 outputs will not work properly unless V1 is loaded (5A min). Connecting just the
+- 15VDC and 12V without the 5VDC will result in the supply failure or incorrect
operation. A digital voltmeter (DVM) may be used to measure the DC terminal voltages
on the power supply. All outputs should be at or above (no more than 10%) their rated
outputs. The + and - 15 VDC outputs should be equal within 10% of each other. Using
the AC setting on the DVM will show any AC ripple or unfiltered noise on the supply
outputs, ripple must be less than 5% on all outputs. An AC line isolated oscilloscope
may be used to visually detect any noise on the power supply outputs. Use extreme
caution when using this method to prevent damage or injury. Always use an isolation
transformer or a battery-powered oscilloscope when troubleshooting with an
oscilloscope.
Safety
Make certain all terminal screws are tightened down, the supply is physically mounted,
wire insulation and lugs are in good condition and no combustible materials are in close
proximity to the power supply. Clean all dust and dirt in and around the supply and its
chassis. Replace all machine covers, safety covers and chassis before attempting to
run the machine.