Omega OM-420 User Manual

USING THE RPS-1in the OM-420

USING THE RPS-1, RECHARGEABLE POWER SUPPLY

IN THE OM-420

OVERVIEW:

The RPS-1 is a self-contained battery power source for use in conjunction with the OM-320/420 System
Base to power transducers requiring external power (e.g. Strain Gages, Pressure transducers, 4 to 20ma
Loop Transmitters, etc.) over a voltage range from 3.5 to 22 VDC.

The RPS-1 contains two User-configurable, rechargeable gel-cell type batteries and integral recharging
circuitry. The charging circuitry will accept AC or DC current from Photovoltaic arrays, wind generators,
utility sourced transformers/plug-in power supplies, or other current sources. The sealed batteries are
capable of operating in any orientation and over a temperature range of -10 to 60C. A slide switch allows
the User to configure the RPS-1 for 12 or 24VDC operation.

Two User-programmable Power Supply outputs are available which can source 7 different regulated
voltage levels from 3.5VDC to 22VDC. Outputs are short circuit / over-current protected.

The two Power Supplies can be independently programmed for output voltage as well as type of
operational mode. Two modes are available, Continuous ON or AUTOMATIC Operation. In AUTOMATIC
Operation, the power supply is under control of an optically isolated low voltage (5VDC, 0.5mA) control
input signal. This control INPUT interfaces directly to a OM-320/420 Digital Output line which can be
programmed to cycle the RPS-1 power supplies ON and OFF, providing transducer excitation under OM­320/420 control during a logging session. This automatic power supply cycling technique maximizes RPS­1 battery life. See Figure 1 for a sample Hypernet

Figure 1: RPS-1 Control Using HyperWare Warm-Up

Icon

Omega Engineering Inc. 1 Stamford, CT

USING THE RPS-1in the OM-420

An integral State-of-Charge (SOC) indicator is provided which will display an approximate Battery State-of­Charge based on battery voltage under a fixed load. Test is actuated by depressing a momentary SOC
Test Switch.

HARDWARE / USER CONTROLS:

Figure 1 illustrates the functional blocks contained within the RPS-1. An explanation of each block follows:

MAIN POWER SWITCH

Provides ON/OFF control of the RPS-1. In the OFF position, the batteries are disconnected from the RPS­1 circuits (power supplies, State-of-Charge indicator, charging circuits, etc.). This switch in either 12 VDC
or 24 VDC ON position selects how the two 12 volt gel-cell batteries are connected (parallel for 12 VDC
nominal output or series for 24 VDC nominal output). Note: For charging, the Main Power switch must be in
either the 12VDC or 24VDC position.

External Power

Battery State of
Charge light bar

Supply Control
Signal

12 V Gel-Cell
BATTERY

Main Power
Switch

Power Supply
A

+

­12 V Gel-Cell
BATTERY

Battery Charging
circuitry

Power Supply
B

hl200-01.ecw

+

-

Figure 2: RPS-1 Functional Block Diagram

CHARGER INPUT

Two terminal connections are provided for connection of an external current source for charging the RPS-1
batteries.

POWER SUPPLY OUTPUTS

Two independent User programmable voltage power supply outputs (A and B) feed the twelve position
terminal strip on the right side of the unit. The top four terminals are all connected to the A supply output
and the middle four to the B supply output. The bottom four terminals are all connected together and to
the COMMON (circuit ground) of the two supplies.

OUTPUT VOLTAGE / MODE SWITCHES

Each of the two power supplies has an eight position DIP switch associated with it. The top seven switches
determine the output voltage for that supply and the last switch (#8) defines the mode of operation (AUTO
or ON) for the power supply.

Omega Engineering Inc. 2 Stamford, CT

USING THE RPS-1in the OM-420

CONTROL INPUT

Two terminal connections are provided for connection of a low voltage power supply control signal. This
input signal controls the ON/OFF cycling of power supplies set to the AUTO mode. Typically, this control
input is controlled by a OM-320/420 Digital Output.

STATE-OF-CHARGE INDICATOR

When the TEST button is depressed, an approximate battery state of charge is displayed on the 10
position Display. This display is based on the battery voltage under a slight load.

INSTALLATION

MOUNTING

The RPS-1 should be mounted in a vertical position in order to optimize rain shedding and prevent direct
spray into the bottom fittings. The enclosure is designed for indoor and outdoor exposure within the
specified temperature limits. Battery life and capacity is at a maximum when the batteries are at a
temperature of 20C (68F). Shading from direct sunlight and/or insulation WITHOUT RESTRICTING AIR
FLOW AROUND THE UNIT can optimize battery life and capacity. During charging, the batteries will emit
small amounts of FLAMMABLE AND EXPLOSIVE HYDROGEN GAS. Additionally, heat is generated by
the voltage regulating circuits. For these two reasons, ventilation around the package will maximize
performance as well as minimize risk of potentially hazardous explosions.

WIRING

The OM-420 is factory configured to use OM-320/420 Digital Output #1 to control the RPS-1.
These connections are as follows: The positive Digital Output (Marked D01 on the TSA) is
connected to the RPS-1 positive CONTROL INPUT terminal.
The negative Digital Output (Marked GND on the TSA) is connected to the RPS-1 negative
CONTROL INPUT terminal. (See Figure 2)

Power Supply wiring should be routed through the liquid-tite fittings in the bottom of the OM-420 enclosure.
For most applications, 18 AWG wire will suffice without excessive voltage drop (18 AWG will result in less
than 0.1 V drop in 100 feet at 150 mA). PVC jacketed multi-conductor wire is a good choice that seals well
in the liquid-tite fittings.

OPERATION / SET-UP

POWER SUPPLIES

Select the desired output voltage for the A and B power supplies from the following table:

1 = 22 VDC
2 = 18 VDC
3 = 15 VDC
4 = 12 VDC
5 = 10 VDC
6 = 5 VDC

7 = 3.5 VDC
Set ONE of the seven VOLTAGE PROGRAMMING switches to the desired choice on each supply. If a
supply is not utilized, set all switches OFF (to the left). Correct voltage setting can be verified with a volt
meter reading from the OUTPUT terminal to the COMMON terminal. ONLY ONE voltage programming
switch should be ON for each supply.

Omega Engineering Inc. 3 Stamford, CT