GENERAL DESCRIPTION:
The Load Managers manufactured by ECX are designed to provide a reliable and accurate means of monitoring and controlling the transfer of energy in an automotive electrical system.
The typical layout of an automotive electrical system is shown in Figure 1:
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Figure 1 shows the main components of the vehicle's electrical network:
ENGINE= Source of mechanical energy (the vehicle's engine).
ALTERNATOR= Source of the electrical energy used in the vehicle (the alternator).
BATTERY= Storage battery used to keep the excess electrical energy not used by the loads.
LOAD= Loads using the electrical energy delivered by the alternator (lights, fans, radios). |
FIGURE 1 |
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The electrical energy produced by the alternator is used to provide power to all the electrical loads in the vehicle (lights, fans, valves, radios, etc.)
Any excess power not used by the loads is stored in the vehicle's battery and remains there for when it is needed (as a power backup when the alternator is not delivering enough power to the loads).
In an ideal vehicle's electrical system, the alternator will always provide all the power required by the connected loads. However, from an economical or engineering point of view, it is not practical to build such a system.
As a result, there will be times when the electrical demand will surpass the available energy supply and the electrical network will not operate as required.
A typical example of the electrical power demand exceeding the available energy delivered by the alternator is the case of an emergency
vehicle arriving at the scene of an accident.
While the vehicle is moving along the highways at its normal speed, with all the emergency lights flashing, the engine/alternator combination
run at such speed that the energy supplied by the alternator is sufficient to meet the load demand imposed by the emergency lights and the
rest of the electrical system.
When the emergency vehicle arrives at the scene, the electrical loads composed of emergency lights, radios, pumps, valves, fans, etc. are still
operating as required but the engine is now running at idle speed and the alternator is unable to supply all the energy required by the loads.
At this time, the energy which is not coming from the alternator will be taken from the battery.
This situation is not sustainable for long periods because there is only a finite amount of energy stored in the battery, When this stored
energy is depleted the loads (many of them critical) will cease to operate (see FIGURE 2).
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Figure 2 shows the main components of the vehicle's electrical network:
ENGINE= Source of mechanical energy (the vehicle's engine).
ALTERNATOR= Source of the electrical energy used in the vehicle (the alternator).
BATTERY= Storage battery used to keep the excess electrical energy not used by the loads
LOAD= Loads using the electrical energy delivered by the alternator (lights, fans, radios). |
FIGURE 2 |
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There are three solutions to this problem:
1) Decrease the number of loads connected.
2) Increase the power delivered by the alternator.
3) Use a combination of (1) and (2) above.
There are two ways to implement the solutions mentioned above:
a) Manually (not practical because the attendants would have to perform this function and neglect their primary duties).
b) Automatically (function performed by ECX's Load Managers).
The typical layout of an automotive electrical system using an ECX Load Manager is shown in
Figure 3:
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Figure 3 shows the main components of the vehicle's electrical network:
ENGINE = Source of mechanical energy (the vehicle's engine).
ALTERNATOR = Source of the electrical energy used in the vehicle (the alternator).
BATTERY = Storage battery used to keep the excess electrical energy not used by the loads.
LOAD = Loads using the electrical energy delivered by the alternator (lights, fans, radios).
LOAD MGR = ECX Load Manager.
(IP) = Indicating Panel. |
FIGURE 3 |
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All load managers manufactured by ECX incorporate the Load Sequencer and Load Shedding functions.
To protect the integrity of the vehicle's electrical system, the ECX Load Managers will:
Use the Load Sequencer function to turn all selected loads ON and OFF from one central switch. It will accomplish this task
in an orderly sequence so as to minimize electrical disturbances and the effect this action may have upon the rest of the electrical system.
Use the Load Shedding function to monitor the voltage level of the vehicle's battery. If a decay in the battery voltage is
sensed, the Load Manager will start shedding loads, following a predetermined sequence, until a power balance is re-established. Once the
power output returns to its normal value, the loads previously shed are re-energized.
Use the High Idle function if the alternator is not supplying enough power when the vehicle is idling. In this case, the Load Manager's High Idle
output becomes active and sends a signal to the Vehicle's engine speed control (provided by others) to set the Idle speed to a higher level.
The higher engine speed is maintained until the battery voltage returns to normal or until the engine is no longer idling.
(See detailed Load Manager Description for specific operational details and programmable features)
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Detailed Load Manager Description
LOAD SEQUENCER FUNCTION:
When electrical loads of the type encountered in an automotive application are switched ON or OFF they create large current and voltage fluctuations in
the electrical system in which they are connected. The larger the current consumption of a load, the greater the impact the load has in the generation
of electrical transients when the load is energized or deenergized.
These current fluctuations, in turn, contribute to the generation of voltage spikes of a magnitude that is high enough to damage sensitive electronic
devices connected to the electrical system.
One or two small loads turned ON or OFF simultaneously may not produce voltage spikes of serious consequences. However, when a larger
number of loads are energized or deenergized simultaneously, the electrical system will undergo a period of instability that could adversely affect
the operation of the electrical network or permanently damage some of its components.
The Load Sequencer feature of ECX's Load Managers turns all selected loads ON and OFF from one central switch. It accomplishes this task in an orderly sequence so as to minimize the effect this action may have upon the rest of the electrical system.
Depending on the ECX Load Manager Model selected, the loads will be turned ON or OFF by:
- following a factory preset sequence with a specific time delay between the energization/deenergization of consecutive loads.
Or:
- following a factory or customer programmable sequence and/or time delay between the energization/denergization of consecutive loads.
LOAD SEQUENCER FEATURES:
| LOAD SEQUENCER OPERATION |
The system turns loads ON and OFF following a specific sequence to avoid subjecting the vehicle's electrical system to extreme load variations in very short intervals. |
| PROGRAMMING OF TIME INTERVAL BETWEEN ACTIVATION (OR DEACTIVATION) OF CONSECUTIVE LOADS |
This time interval is factory or customer programmable using built-in switches or by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| SEQUENCE LOADS "ON" OR "OFF" INPUT |
Signal provided by a customer supplied toggle switch that commands the system to turn the loads ON or OFF, one at a time, according to the priority assigned to each of them. |
| SETTING OF "POWER ON" LOAD SEQUENCING PRIORITIES |
The sequence in which loads are turned ON is established in some Load Manager models by wiring the load to be activated first to the output terminal L1, the second load to terminal L2, etc. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| SETTING OF "POWER OFF" LOAD SEQUENCING PRIORITIES |
The sequence in which loads are turned OFF is established in some Load Manager models by wiring the load to be activated first to the output terminal L1, the second load to terminal L2, etc. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| SELECTION OF LOADS TO BE SEQUENCED "ON" AND "OFF" |
The sequence in which loads are turned OFF is established in some Load Manager models by wiring the load to be activated first to the output terminal L1, the second load to terminal L2, etc. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
LOAD SHEDDING FUNCTION:
To ensure the stability of the electrical system, ECX Load Managers monitor the output of the power source. If a decay in the power output is sensed, the Load Manager will start shedding loads, following a predetermined sequence, until a power balance is re-established. Once the power output returns to its normal value, the loads previously shed are re-energized.
LOAD SHEDDING FEATURES:
| LOAD SHEDDING OPERATION |
When the battery voltage level is below its normal state, the system turns loads ON and OFF as a function of the value of the lower voltage levels reached or as a function of the time elapsed since the start of the battery voltage drop. |
| SETTING OF LOAD SHEDDING PRIORITIES |
The sequence in which loads are shed or turned ON/OFF is established in some Load Manager models by means of built-in programming switches.. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| LOAD SHEDDING ENABLE INPUT |
This signal is provided by a customer supplied toggle switch. It is used to turn the Load shedding function ON/OFF. Loads will then be shed and reconnected according to the operational requirements established. |
| SYSTEM OVERRIDE INPUT |
This signal is provided by a customer supplied pushbutton or toggle switch. It will turn all the outputs ON, regardless of the setting of any other control signal. It can be used as a TEST switch to verify the operation of all outputs. |
| LOAD SHEDDING OPERATION BASED ON DURATION OF VOLTAGE DROP |
The shedding of a load is based on the time elapsed since the battery voltage reached a new lower voltage threshold. Similarly, the reconnection of a load previously shed is based on the time elapsed since the battery voltage reached a new higher voltage threshold. |
| PROGRAMMABLE LOAD SHEDDING TIME INTERVAL |
The time interval in which loads are shed or turned ON/OFF is established in some Load Manager models by means of built-in programming switches.. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| LOAD SHEDDING OPERATION BASED ON MAGNITUDE OF BATTERY VOLTAGE DROP |
The shedding function is based on the value of the lower battery voltage threshold reached. Similarly, the reconnection of a load previously shed is a function of the value of the new higher battery voltage threshold reached. |
| PROGRAMMABLE LOAD SHEDDING BATTERY VOLTAGE LEVELS |
The voltage levels at which loads are shed or turned ON/OFF is established in some Load Manager models by means of built-in programming switches.. Other models accomplish this by downloading data tables using a PC or an optional ECX hand-held programming unit. |
Operational Details
LOAD MANAGER INPUTS:
The Load Sequencer and Load Shedding functions operate in response to the value of the vehicle's battery voltage and to input signals derived from switches or pushbuttons actuated by the operator.
An input signal will be considered as being "Active" when it connects the corresponding Load Manager input to either Ground or +12V or 24V. This flexibility
in input signal polarity allows the load manager to be connected with ease in a variety of applications.
The number, type and function performed by each input is listed below and in the comparison table describing the features of each Load Manager Model.
INPUT CHARACTERISTICS:
| NUMBER OF INPUTS |
Total number of input control signals that can be used to tell the Load Manager what actions to take. (See individual input descriptions below). These input signals are derived from customer supplied toggle switches. |
| POLARITY OF INPUTS |
All ECX Load Managers will accept input signals that are considered to be "active" when connected to either +12/24V or Ground. |
| PROGRAMMABLE INPUT POLARITY |
The polarity of each input signal must be programmed into the Load Manager. This is accomplished using built-in switches or by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| MANUAL BYPASS INPUT |
This signal is provided by a customer supplied or toggle switch. It will turn all the outputs ON of OFF, regardless of the setting of any other control signal. It can be used as a TEST switch to verify the operation of all outputs. |
| PARK/NEUTRAL INPUT |
This signal is provided by a customer supplied switch. It is used to enable the Load Manager to respond differently depending on weather the vehicle is in motion or parked). |
| HIGH IDLE DISABLE INPUT |
Signal provided by a customer supplied toggle switch. It is used to disable the High Idle operation when code procedures require the operator to do so or when it is not desirable that the engine be accelerated to compensate for a drop in battery voltage. |
| SEQUENCE LOADS "ON" OR "OFF" INPUT |
Signal provided by a customer supplied toggle switch that commands the system to turn the loads ON or OFF, one at a time, according to the priority assigned to each of them. |
| LOAD SHEDDING ENABLE INPUT |
This signal is provided by a customer supplied toggle switch. It is used to turn the Load shedding function ON/OFF. Loads will then be shed and reconnected according to the operational requirements established. |
| SPARE INPUT |
This signal is provided by a customer supplied pushbutton or toggle switch. It is used to initiate the performance of a customer defined protocol that was previously factory programmed into the Load Manager. |
LOAD MANAGER OUTPUTS:
The Load Manager outputs are used to energize or de-energize external relays (customer supplied). These relays are used in the customer's network
to control the loads requiring Load Management and Sequencing.
Depending on the Load Manager Model selected, the outputs con control relays requiring up to 0.4 A at 12VDC or 24VDC. It is also possible to operate or drive
customer loads directly with a maximum capacity of 20A at 12VDC or 24VDC for each output.
All Load Manager Models have outputs internally protected against overcurrent and short circuits. It is not necessary for the customer to install
external fuses.
Depending on the Load Manager model selected, output signals are connected to either Ground or +12/24V in the "Active" mode. This flexibility
in output signal polarity allows the load manager to be connected with ease in a variety of applications.
The number, type and function performed by each output is listed below and in the comparison table describing the features of each Load Manager Model.
OUTPUT CHARACTERISTICS:
| NUMBER OF OUTPUTS |
Total number of external circuits that can be controlled. Depending on the Load Manager model selected, they range from 8 to 16. |
| POLARITY OF OUTPUTS |
Depending on the Load Manager model selected, outputs are active at 12/24 VDC or Ground. A "12/24V" polarity Indicates that the output will "source" current to loads connected to Ground. A "GND" polarity indicates that the output will "sink" current from loads connected to 12/24VDC). |
| PROGRAMMABLE OUTPUT POLARITY |
Some Load Manager models allow the polarity selection for each individual output. This function is factory or customer programmable by downloading data tables using a PC or an optional ECX hand-held programming unit. |
| CURRENT CARRYING CAPACITY OF EACH OUTPUT |
Each output will drive external automotive relays rated at 12/24VDC and up to 0.4A. Additionally, the Load Manager Model LM-D will source 20A at 12/24VDC to grounded lights or motor loads. |
| OUTPUTS INTERNALLY PROTECTED AGAINST OVERCURRENTS AND SHORTCIRCUITS |
All outputs in all Load Manager models are internally protected against overcurrents and short circuits |
| REQUIRES EXTERNAL RELAYS TO DRIVE HIGHER CURRENT LOADS |
All Load Managers (except Model LM-D) require external customer supplied relays to drive loads rated at more than 12/24VDC or 0.4A. Load Manager Model LM-D will drive 20A loads at 12/24VDC directly connected to its output terminals. |
| CAPABLE OF GRADUALLY ENERGIZING AND DE-ENERGIZING LOADS TO AVOID CURRENT PEAKS |
Load Manager Model LM-D can gradually turn loads ON and OFF using PWM techniques. This is in addition to all the other regular operational features common to all modules. |
LOAD MANAGER INDICATING/CONTROL PANEL:
The Load Manager operation can be monitored by means of a remotely mounted Indicating Panel. This panel contains lights (LED's) that show when the Load Shedding function is active, when loads are being shed and when there is a malfunction in the equipment.
Some Load Manager models can be factory or field programmed to perform indicating functions different from the ones indicated above.
Higher end Load Manager models offer a touch-screen type color LCD panel that displays the status of sequencing and load management operations. It also allows the operator to enter a variety of commands (bypass, start sequence, change load priorities, change load thresholds, etc.) directly form the touch-screen, eliminating the need for external switches.
INDICATING/CONTROL PANEL CHARACTERISTICS:
| REMOTE LED INDICATOR PANEL |
Houses LED indicators showing the status of sequencing and load shedding operations. |
| PROGRAMMABLE LED INDICATING PANEL |
This type of panel permits the individual programming of each LED to provide customer specific indications. |
| OPTIONAL REMOTE COLOR GRAPHIC DISPLAY AND CONTROL PANEL |
Touch-screen type color LCD panel that displays the status of sequencing and load shedding operations. It also allows the operator to enter operational commands (bypass, start sequence, change load priorities, change load thresholds, etc.) |
LOAD MANAGER NETWORKING:
Some Load Manager models include a Networking feature that allows the unit to become part of a multiplexed control network and exchange information with other devices in the system.
LOAD MANAGER IDLE CONTROL:
If the alternator is not supplying enough power when the vehicle is idling then the Load Manager's High Idle output becomes active and
sends a signal to the Vehicle's engine speed control (provided by others) to set the Idle speed to a higher level.
IDLE CONTROL CHARACTERISTICS:
| HIGH IDLE CONTROL |
This feature signals the vehicle's Speed Control system (provided by others) to increase the engine idle speed and, therefore, the alternator output when a drop in battery voltage is sensed. The higher engine speed is maintained thru the load management cycle and until the battery voltage returns to normal |
| HIGH / LOW VOLTAGE MONITOR |
The battery voltage is monitored. If the voltage level reaches a value above or below preset values an output is activated sending a signal to a customer supplied relay or alarm device. |
| PROGRAMMABLE HIGH / LOW BATTERY VOLTAGE LEVEL ALARM |
All Load Manager models (except LM-A) have High/Low battery voltage levels that can be programmed either at the factory or in the field using a PC or an optional handheld ECX programming unit. |
HIGH/LOW VOLTAGE ALARM:
The high/low voltage alarm feature available in some Load Manager models provides an output that becomes active when the battery voltage
is above or below preset levels. This signal is used to activate an audible or visual alarm device supplied by the customer.
HIGH/LOW VOLTAGE ALARM CHARACTERISTICS:
HIGH / LOW VOLTAGE MONITOR |
The battery voltage is monitored. If the voltage level reaches a value above or below preset values an output is activated sending a signal to a customer supplied relay or alarm device. |
PROGRAMMABLE HIGH / LOW BATTERY VOLTAGE LEVEL ALARM |
All Load Manager models (except LM-A) have High/Low battery voltage levels that can be programmed either at the factory or in the field using a PC or an optional handheld ECX programming unit. |
LOAD MANAGER PROGRAMMING:
Customer changes are implemented either by using built-in selector switches or by downloading the appropriate ECX software from
a PC or a Hand-held device.
FIELD CONNECTION DIAGRAMS:
Model: ECX LM-A
Model: ECX LM-B
Model: ECX LM-C
Model: ECX LM-D
COMPARATIVE OF FEATURES FOR ALL MODELS:
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