4. Features and Functions¶
4.1. Set-Points¶
Set-points are user reference values that describe the desired steady-state operation of the MagnaLOAD electronic load. In combination with the feedback Regulation States, the difference between the set-point and corresponding measurements are driven to zero over time. Some set-points will be disabled in menus or have no effect on the operation. For example, in Constant Current Mode, voltage feedback is disabled, and the voltage set-point has no impact on the operation of the MagnaLOAD electronic load.
4.2. Commands¶
The ARx Series MagnaLOAD DC electronic load features a variety of commands, which can all be accessed from the front panel, external user I/O, and computer interface.
4.2.1. Start¶
The Start command engages the MagnaLOAD electronic load’s DC input to allow the product to begin dissipating power, transitioning the status from Disabled to Enabled. The Start command switches the dissipative elements into of the DC circuit using a high-speed switching device.
4.2.2. Stop¶
The Stop command disengages the MagnaLOAD electronic load’s DC input to stop the product from dissipating power, transitioning the status from Enabled to Disabled. The Stop command switches the dissipative elements out of the DC bus using a high speed switching device.
Warning
Even when the Stop command is issued and the MagnaLOAD electronic load’s status is Disabled, there could still be hazardous voltages on the DC input from an externally connected DC source. Ensure that all instrument connections, load wiring, and load connections are either insulated or covered so that no accidental contact with lethal output voltages can occur. Always use a voltmeter to test the DC bus before making any connections.
4.2.3. Clear¶
The Clear command unlatches all soft-faults conditions and returns the MagnaLOAD electronic load to standby, allowing the user to resume normal operation of the product. All soft-fault conditions must be resolved before clearing the latch. Once the fault has been cleared, the input can be re-enabled with the Start command.
4.2.4. Lock¶
The Lock command secures settings by locking the MagnaLOAD electronic load, preventing changes to set-points and configuration settings through the front panel. When the MagnaLOAD electronic load is locked, the front panel Lock button is back-lit red. In addition, the Lock status can be configured as one of the external user I/O digital outputs or queried by computer interface.
4.3. Function Generator¶
The function generator makes the ARx Series MagnaLOAD DC electronic load sink current according to an internally generated waveform. This feature simplifies dynamic-load test setups since the generation is self contained and conveniently customized through the front panel menu system. Each of the function types available have a different signal-processing algorithm for accepting input parameters and outputting a periodic signal.
The function generator is enabled by choosing it as a Setpoint Source through menus System Settings - Setpoint Source - Function Generator. Once enabled, all set point changes from other sources are ignored. The generator algorithm, selected through menus Function Generator - Function Type, is subject to limitations of the sample rate and look-up table size. The algorithm can update at a rate of 0.5 ms. As such, the period is limited such that 4 samples are output per period (2 ms). The maximum period is restricted to 65000 ms. Set point related parameters (Amplitude, LoLevel, Offset, etc.) are limited to the product’s rated current.
4.3.1. Sinusoid¶
The sinusoid function produces its waveform using the direct digital synthesis (DDS) method. Set points are loaded from a 1024 point sinusoid lookup table and scaled at fixed-sample intervals. The function is selected through menus Function Generator - Function Type - Sinusoid. The amplitude is set through menus Function Generator - Function Type - Sinusoid Parameters - Amplitude(Adc). From the same parent menu, offset and period are set in menus Offset(Adc) and Period(ms), respectively. These parameters and their effect on the waveform are illustrated in Fig. 4.1.
4.3.2. Square¶
The square function produces its waveform by logically changing set points after a programmed period of time. The function is selected through menus Function Generator - Function Type - Square. The low-level set point is programmed through menus Function Generator - Function Type - Square Parameters - LoLevel(Adc). From in the same parent menu, offset and period, in menus Offset(Adc) and LoPeriod(ms), respectively, are programmed. These parameters and their effect on the waveform are illustrated in Fig. 4.2.
4.3.3. Step¶
The step function behaves similarly to the Square Function, but step points cycle manually by pressing the start button. The first time the start button is pressed, the MagnaLOAD electronic load is enabled, and regulates to the parameter saved in LoLevel(Adc). Pressing the start button again changes the set point to HiLevel(Adc). Pressing the button a third time cycles back to LoLevel(Adc). The parameter effects on the waveform are illustrated in Fig. 4.3.
4.3.4. Ramp¶
The ramp function produces its waveform by logically changing set points after a programmed period of time, while maintaining specified rise and and fall time. The function is selected through menus Function Generator - Function Type - Ramp The low level set point is programmed through menus Function Generator - Function Type - Ramp Parameters - LoLevel(Adc). From the same parent menu, the high level and rise and fall periods, HiLevel(Adc), RiseTime(ms) and FallTime(ms), are set respectively. These parameters and their effect on the waveform are illustrated in Fig. 4.4.
4.4. Operating Profile¶
With its combination of resistor and linear elements, the ARx Series MagnaLOAD DC electronic load provides two distinct user configurable operating profiles: High Power Range and Low Power Range.
The operating profiles figures below apply to to all ARx Series models, normalized about the model’s maximum voltage, current, and power ratings.
In the event the user programs the unit to operate in region outside the operating curve, the MagnaLOAD electronic load will automatically limit its throughput to prevent any possible damage. This internal limiting will be indicated on the front panel auxiliary display, on the message line as: Operating profile limit reached.
4.4.1. High Power Range¶
In High Power Range, the both resistor matrix and linear devices are operating simultaneously to dissipate power.
Fig. 4.5 ARx Series MagnaLOAD DC electronic load Normalized High Power Range Operating Profile
4.4.2. Lower Power Range¶
In Low Power Range, the resistor matrix is bypassed, providing dissipation only through the linear devices. Low Power Range provides a means to achieve the MagnaLOAD electronic load’s full rated current at low voltages. The power limit in Low Power Range is 10% of the MagnaLOAD electronic load’s full scale rated power.
Fig. 4.6 ARx Series MagnaLOAD DC electronic load Normalized Low Power Range Operating Profile
4.5. Control Modes¶
The ARx Series MagnaLOAD DC electronic load automatically selects the appropriate regulation state depending on the selected control mode, programmed set-points and the voltage and current being driven by the connected DC source. The MagnaLOAD electronic load preferences regulation states depending on the selected Control Mode: Voltage Mode, Current Mode, Power Mode, or Resistance Mode.
Control Modes can be selected from the front panel menu system or by computer command. Changing the Control Mode while the DC input is enabled will cause the MagnaLOAD electronic load to stop processing power and enter Disabled status.
4.5.1. Voltage Mode¶
When Voltage Mode is selected, the MagnaLOAD electronic load will auto-crossover between voltage and power regulation, but will preference constant voltage regulation over all other states. In Voltage Mode, the MagnaLOAD electronic load will try to sink enough current to maintain the voltage set point in a constant voltage regulation state. The operating region for Voltage Mode is further described by Fig. 4.7. Programming a resistance set-point and current set-point is disabled in Voltage Mode as the two regulation states conflict with the voltage regulation state.
Trip-point settings for voltage and power can also be used to shutdown the MagnaLOAD electronic load when a programmed threshold is crossed.
Caution
Configuring the MagnaLOAD electronic load for Voltage Mode while the connected DC source is also trying to regulate voltage will produce regulation instabilities. Instead, an alternative control mode should be selected.
Fig. 4.7 Simplified Voltage Mode Operation Diagram. Refer to Fig. 4.5 for operating profile constraints.
4.5.2. Current Mode¶
When Current Mode is selected, the MagnaLOAD electronic load will auto-crossover between current and power regulation, but will preference constant current regulation over all other states. In Current Mode, the MagnaLOAD electronic load will allow the input voltage fluctuate while trying to maintain the current set-point in a constant current regulation state. The operating region for Current Mode is further described by Fig. 4.8. Programming a resistance set-point and voltage set-point is disabled in Current Mode as the two regulation states conflict with the current regulation state.
Trip-point settings for current and power can also be used to shutdown the MagnaLOAD electronic load when a programmed threshold is crossed.
Caution
Configuring the MagnaLOAD electronic load for Current Mode while the connected DC source is also trying to regulate current will produce regulation instabilities. Instead, an alternative control mode should be selected.
Fig. 4.8 Simplified Current Mode Operation Diagram. Refer to Fig. 4.5 for operating profile constraints.
4.5.3. Power Mode¶
When Power Mode is selected, the MagnaLOAD electronic load will auto-crossover between current and power regulation, but will preference constant power regulation over all other states. In Power Mode, the MagnaLOAD electronic load will allow the input voltage and current fluctuate while trying to maintain the power set-point in a constant power regulation state. The operating region for Power Mode is further described by Fig. 4.9. Programming a resistance set-point and voltage set-point is disabled in Current Mode as the two regulation states conflict with the current regulation state.
Trip-point settings for current and power can also be used to shutdown the MagnaLOAD electronic load when a programmed threshold is crossed.
Caution
Configuring the MagnaLOAD electronic load for Power Mode while the connected DC source is also trying to regulate power will produce regulation instabilities. Instead, an alternative control mode should be selected.
Fig. 4.9 Simplified Power Mode Operation Diagram. Refer to Fig. 4.5 for operating profile constraints.
4.5.4. Resistance Mode¶
When Resistance Mode is selected, the MagnaLOAD electronic load will preference Constant Resistance (CR) regulation state over all other regulation states. The MagnaLOAD electronic load will operate in constant resistance regulation within the set-point boundaries indicated in grey in Fig. 4.10. If the connected DC source drives the DC bus to one of the bounding set-point limits, the MagnaLOAD electronic load will auto-crossover to the appropriate regulation state. To avoid auto-crossover, the bounding set-point limits should be set sufficiently high to increase the constant resistance operating range. Programming a current set-point and voltage set-point is disabled in Resistance Mode as the two regulation states conflict with the resistance regulation state. trip-point-settings for voltage, current, and power can also be used to shutdown the MagnaLOAD electronic load when a maximum desired limit is reached.
Fig. 4.10 Simplified Resistance Mode Operation Diagram. Refer to Fig. 4.5 for operating profile constraints.
4.5.5. Shunt Regulator Mode¶
Shunt Regulator Mode is designed to regulate the DC bus voltage to ensure the voltage remains below a programmed limit. Shunt Regulator Mode can be used as a replacement for a braking resistor in a DC motor drive application, or as a protection device to prevent rising DC bus voltage from damaging other electronic devices.
When Shunt Regulator Mode is selected, the MagnaLOAD electronic load will only dissipate energy when the voltage passes a user-defined voltage threshold. The MagnaLOAD electronic load will remain idle at the DC bus voltage defined by the source until that DC bus voltage rises above a programmed voltage threshold. When DC bus voltage passes this voltage threshold, the MagnaLOAD electronic load will begin to process power, with the current rising rapidly to the current set point.
The voltage threshold is the programmed voltage set point plus 1% of the unit’s full scale voltage rating. For example, if an ARx6.75-1000-14 (6.75 kW, 0-1000 Vdc, 0-14 Adc) MagnaLOAD electronic load was programmed to 500 Vdc in Shunt Regulator Mode, the MagnaLOAD electronic load would begin dissipating energy at the voltage threshold: 500 Vdc + (1% of 1000 Vdc) = 510 Vdc. The MagnaLOAD electronic load would continue dissipating energy until the DC bus voltage drops below 500 Vdc.
When the product is dissipating energy in Shunt Regulator Mode, the current is regulated to the MagnaLOAD electronic load’s user-defined current set point.
Note
If the MagnaLOAD electronic load is not sized properly for the amount of current fed back onto the DC bus, the voltage on the DC bus may continue to rise beyond the MagnaLOAD electronic load’s voltage threshold.
Fig. 4.11 shows the voltage and current over time in Shunt Regulator Mode, as the DC bus voltage rises below the voltage threshold and the MagnaLOAD electronic load begins dissipating energy. trip-point-settings for voltage, current, and power can also be used to shutdown the MagnaLOAD electronic load when a maximum desired limit is reached.
Fig. 4.11 Simplified Shunt Regulator Mode Operation Diagram. Refer to Fig. 4.5 for operating profile constraints.
4.5.6. Rheostat Mode¶
The power dissipation stage in the ARx Series MagnaLOAD DC electronic load consists of a switched matrix of resistors coupled with linear elements, as described in Principle of Operation. Rheostat Mode bypasses the linear elements to provide direct control of the MagnaLOAD electronic load’s switched resistor matrix. A total of 31 different resistor states are available. Each resistor state has an associated power limit, less than the MagnaLOAD electronic load’s full scale rated power, which cannot be exceeded. Resistor states can be switched on-the-fly, with the DC input enabled, at the resistor state’s maximum power rating. The full scale rated output voltage or full scale rated output current can be achieved at each resistor state, as long as that resistor state’s power limit is not exceeded.
Note
Exceeding the the maximum power rating for any given resistor state will result in an over power trip fault.
The 31 available Rheostat resistance values vary by model. For a single resistor state on a specific model, the resistance value is calculated as follows:
For example, referring to the tables below, to calculate the resistance value for the ARx15-500-60 in resistor state 3:
Therefore, at resistor state 3 the ARx13.5-500-56 is 4.30 Ω and is capable of dissipating up to 500 Vdc, up to 56 Adc, but never exceeding 10.8 kW (80% of its 13.5 kW full scale power rating)
The following table provides a list of Reference Resistance values for each model:
| Model | Reference Resistor Value |
|---|---|
| ARx6.75-100-140 | 0.30 Ω |
| ARx6.75-200-70 | 1.17 Ω |
| ARx6.75-500-28 | 7.47 Ω |
| ARx6.75-1000-14 | 29.87 Ω |
| ARx13.5-100-280 | 0.15 Ω |
| ARx13.5-200-140 | 0.59 Ω |
| ARx13.5-500-56 | 3.74 Ω |
| ARx13.5-1000-28 | 14.94 Ω |
| ARx20.25-100-420 | 0.10 Ω |
| ARx20.25-200-210 | 0.39 Ω |
| ARx20.25-500-84 | 2.49 Ω |
| ARx20.25-1000-42 | 9.96 Ω |
| ARx27-100-560 | 0.08 Ω |
| ARx27-200-280 | 0.29 Ω |
| ARx27-500-112 | 1.87 Ω |
| ARx27-1000-56 | 7.47 Ω |
| ARx33.75-100-700 | 0.06 Ω |
| ARx33.75-200-350 | 0.23 Ω |
| ARx33.75-500-140 | 1.49 Ω |
| ARx33.75-1000-70 | 5.97 Ω |
| ARx40.5-100-840 | 0.05 Ω |
| ARx40.5-200-420 | 0.20 Ω |
| ARx40.5-500-168 | 1.25 Ω |
| ARx40.5-1000-84 | 4.98 Ω |
The following table provides a list of Resistor Multiplier values, used to determine what resistor values are available and the maximum operating power at the respective resistor setting:
| Resistor State | Resistor Multiplier | Maximum Power Rating (Percent of Full Scale Power) |
|---|---|---|
| 1 | 1.00 | 80% |
| 2 | 1.07 | 80% |
| 3 | 1.15 | 80% |
| 4 | 1.25 | 80% |
| 5 | 1.36 | 80% |
| 6 | 1.50 | 80% |
| 7 | 1.67 | 80% |
| 8 | 1.88 | 80% |
| 9 | 2.00 | 80% |
| 10 | 2.14 | 80% |
| 11 | 2.31 | 80% |
| 12 | 2.50 | 80% |
| 13 | 2.73 | 80% |
| 14 | 3.00 | 80% |
| 15 | 3.33 | 80% |
| 16 | 3.75 | 80% |
| 17 | 4.00 | 80% |
| 18 | 4.29 | 80% |
| 19 | 4.62 | 80% |
| 20 | 5.00 | 80% |
| 21 | 5.45 | 80% |
| 22 | 6.00 | 80% |
| 23 | 6.67 | 80% |
| 24 | 7.50 | 80% |
| 25 | 8.57 | 40% |
| 26 | 10.0 | 33% |
| 27 | 12.00 | 26% |
| 28 | 15.00 | 22% |
| 29 | 20.00 | 16% |
| 30 | 30.00 | 11% |
| 31 | 60.00 | 5% |
4.6. Regulation States¶
The ARx Series MagnaLOAD DC electronic load has four regulation states: Constant Voltage (CV), Constant Current (CC), Constant Power (CP), and Constant Resistance (CR). The active regulation state is indicated by a illuminated circular LED next to the respective voltage, current, power, or resistance set-point button. The active regulation state can also be monitored programmatically.
4.6.1. Constant Voltage (CV)¶
When the constant voltage regulation state is indicated, the MagnaLOAD electronic load is maintaining fixed voltage set-point, while the current flucuates with the driving DC source, as illustrated by Fig. 4.12.
Fig. 4.12 Operating range in constant voltage mode
4.6.2. Constant Current (CC)¶
When the constant current regulation state is indicated, the MagnaLOAD electronic load is maintaining a fixed current set-point, while the voltage flucuates with the driving DC source, as illustrated by Fig. 4.13.
Fig. 4.13 Operating range in constant currnet mode
4.6.3. Constant Power (CP)¶
When the constant power regulation state is indicated, the MagnaLOAD electronic load is maintaining a fixed power set-point by varying the current level inversely in response to a change in input voltage, as illustrated by Fig. 4.14.
Fig. 4.14 Operating range in constant power mode
4.6.4. Constant Resistance (CR)¶
When the constant resistance regulation state is indicated, the MagnaLOAD electronic load is maintaining a fixed resistance set-point, by sinking input current linearly proportional the input voltage, as illustrated by Fig. 4.15.
Note
The constant resistance regulation state will only be indicated when the MagnaLOAD electronic load is configured for Resistance Mode.
Fig. 4.15 Operating range in constant resistance mode
4.7. Protection and Diagnostics¶
4.7.1. Over Voltage Trip (OVT)¶
The ARx Series MagnaLOAD DC electronic load has a programmable Over Voltage Trip setting used to shutdown the product if an undesired maximum voltage value is measured across the DC input. The OVT setting can be adjusted to a maximum of 110% of the specific MagnaLOAD electronic load’s full scale voltage rating. An over-voltage condition must be sustained for multiple samples for the OVT fault to register.
When an OVT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the MagnaLOAD electronic load in an open-circuit faulted condition with an OVT alarm shown on the auxiliary display. To resume operation, the DC input voltage must be drop below the MagnaLOAD electronic load’s OVT setting, the Clear function must be issued, and the input re-energized with the Start function.
The OVT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default OVT setting is 110% of the specific MagnaLOAD electronic load’s maximum voltage rating.
4.7.2. Under Voltage Trip (UVT)¶
The ARx Series MagnaLOAD DC electronic load has a programmable Under Voltage Trip setting used to shutdown the product if an undesired minimum voltage threshold is measured across the DC input. The UVT setting can be adjusted to a minimum of 5% of the specific MagnaLOAD electronic load’s full scale voltage rating. An under-voltage condition must be sustained for multiple samples for the UVT fault to register.
The UVT setting was designed to protect DC input sources, such as batteries, from discharging below a minimum desired voltage. If the UVT setting is used, upon first enabling the DC input the DC input voltage must be above the UVT setting or the MagnaLOAD electronic load will trip immediately. Fig. 4.16 shows the operating range with both OVT and UVT enabled.
Fig. 4.16 Operating region without trip when OVT and UVT settings are enabled
When an UVT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the MagnaLOAD electronic load in an open-circuit faulted condition with an UVT alarm shown on the auxiliary display. To resume operation, the Clear function must be issued and the input re-energized with the Start function.
The UVT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default UVT setting is 0 Vdc, which disables the UVT protection.
4.7.3. Over Current Trip (OCT)¶
The ARx Series MagnaLOAD DC electronic load has a programmable Over Current Trip setting used to shutdown the product if an undesired maximum current value is measured through the DC input. The OCT setting can be adjusted to a maximum of 110% of the specific MagnaLOAD electronic load’s full scale voltage rating. An over current condition must be sustained for multiple samples for the OCT fault to register.
When an OCT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the MagnaLOAD electronic load in an open-circuit faulted condition with an OCT alarm shown on the auxiliary display. To resume operation, the DC input current must be drop below the MagnaLOAD electronic load’s OCT setting, the clear function must be issued, and the input re-energized with the start function.
The OCT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
4.7.4. Over Power Trip (OPT)¶
The ARx Series MagnaLOAD DC electronic load has a programmable Over Power Trip setting used to shutdown the product if an undesired maximum power value is measured at the DC input. The OPT setting can be adjusted to a maximum of 110% of the specific MagnaLOAD electronic load’s full scale power rating. An over-power condition must be sustained for multiple samples for the OPT fault to register.
When an OPT fault occurs, the DC input bus is disconnected via an internal switching device, leaving the MagnaLOAD electronic load in an open-circuit faulted condition with an OPT alarm shown on the auxiliary display. To resume operation, the DC input voltage must be drop below the MagnaLOAD electronic load’s OPT setting, the Clear function must be issued, and the input re-energized with the Start function.
The OPT setting can be programmed through the front panel’s auxiliary display, through one of the four analog inputs, or programmatically through software.
The factory default OPT setting is 110% of the specific MagnaLOAD electronic load’s maximum power rating.
4.7.5. Thermal Fault¶
The ARx Series MagnaLOAD DC electronic load has internal thermistors on its various heatsinks to ensure operation at temperatures within the product’s design specifications. A thermal fault typically results from one of the following conditions:
- Operating in an environment above the maximum ambient temperature specification.
- Operating in an environment below the minimum ambient temperature specification.
- Blocking the front panel air intake.
- Internal fan or solenoid failure.
- Broken electrical contact to thermistors.
- Coolant intake temperatures are above those recommended.
When a thermal fault occurs, the MagnaLOAD electronic load enters into a hard-fault condition, where all loads disconnect from the source. The user is prevent from enabling the load through the front panel and external interfaces. Details about the thermal fault are shown on the front display.
To resume operation, the product must be power cycled, by toggling the rocker switch located on the front panel. Allow sufficient time for the MagnaLOAD electronic load to return to safe operating temperatures. Otherwise, the product will enter immediately into a thermal fault after booting.
4.7.6. Interlock¶
The Interlock feature disables the MagnaLOAD electronic load by entering a soft fault state. The safety feature is triggered whenever the +5V signal applied to the interlock pin is broken. By default, interlock is disabled when the MagnaLOAD electronic load ships from the factory. Interlock can be enabled from the front panel, computer interface. Once interlock is assigned to one of the pins listed in external user I/O +5V must be present to operate the product. There are two method to providing +5V to the interlock pin:
- Providing a physical short from the provided external user I/O +5V signal (Pin 14) to the interlock digital input.
- Using an external user supplied +5V signal with reference to the external user I/O GND signal (Pin 25).
With either method, an external dry contact may be used to trigger the interlock.
When the +5V interlock signal is broken, the dissipative elements are switched out of the DC bus using a high-speed switching device, the MagnaLOAD electronic load is placed in a soft fault state.
To resume normal operation, the +5V signal must first be restored to the interlock input and the Clear command issued.
4.7.7. Lock¶
The lock feature prevents inadvertent changes to MagnaLOAD electronic load operation by disabling front panel button inputs. Lock can be enabled through the front panel using the LOCK button, through the communications interface using SCPI commands, and the rear-external interface using a +5V signal. In all cases, the LOCK button will illuminate to show the MagnaLOAD electronic load is lock. Also, and the stop button always functions normally (for safety). The digital input lock takes highest priority, such that when locked, it can be unlocked only by the digital input. Second priority is SCPI followed by the LOCK button. The table below illustrates unlocking behavior for a locked MagnaLOAD electronic load.
| Locked by Front Panel | Locked by SCPI | Locked by Digital Input | |
|---|---|---|---|
| Front Panel Unlock | ✓ | ||
| SCPI Unlock | ✓ | ✓ | |
| Digital Input Unlock | ✓ |
4.8. Statuses¶
The MagnaLOAD electronic load has various statuses corresponding to its present state of operation. These statuses can be viewed on the front panel, programmatically by computer command, or using the 25-pin user I/O connector. The available statuses are as follows:
- Enabled
- The MagnaLOAD electronic load’s input is engaged and processing power.
- Disabled
- The MagnaLOAD electronic load’s input is disengaged and all systems are normal. The MagnaLOAD electronic load is awaiting a START command to engage its input. When in a Disabled state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
- Soft Fault
- The MagnaLOAD electronic load’s input is disengaged as a result of a soft fault that occurred. A soft fault occurs when an user-programmed limit is reached, such as a trip setting. A description of the soft fault is displayed on the message line. A soft fault can be cleared with the CLEAR function, placing the MagnaLOAD electronic load into a Disabled status. When in a Soft Fault state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
- Hard Fault
- The MagnaLOAD electronic load’s input is disengaged as a result of a hard fault that occurred. A hard fault is a system shutdown resulting from an operating condition that has the potential to damage the product, for example, exceeding the products specifications. A description of the hard fault is displayed on the message line. A hard fault fault can only be cleared by power cycling the product. When in a Hard Fault state, there is an electrical disconnect between the product’s dissipative elements and the DC input terminals through a high speed switching device.
Caution
Ignoring hard faults and repeatedly operating the MagnaLOAD electronic load in a manner that triggers a hard fault will eventually result in product damage.
4.9. Status Messages¶
The MagnaLOAD electronic load has various messages, which elaborate on the product’s present status. A message may indicate normal operation, power limiting as a result of the MagnaLOAD electronic load’s operating profile, or steps to resolve a fault.
Messages for Status: Enabled
- Systems normal.
- Operating profile limit reached. Limiting resistor power throughput.
- Operating profile limit reached. Limiting MOSFET power throughput.
Messages for Status: Disabled
- System disabled.
Messages for Status: Soft Fault
- Voltage trip point setting reached. Issue CLEAR command to resume operation in standby.
- Current trip point setting reached. Issue CLEAR command to resume operation in standby.
- Power trip point setting reached. Issue CLEAR command to resume operation in standby.
- Resistance trip point setting reached. Issue CLEAR command to resume operation in standby.
Messages for Status: Hard Fault
- Global shutdown occurred. Power cycle to resume operation in Standby.
- Chopper stage currents exceeded product rating. Verify load does not exceed product ratings.
- Excessive communication errors detected. Check cabling and communications grounding. Contact technical support.
- Voltage measured that exceeds product’s max rating. Investigate cause and power cycle to resume operation in standby.
- Current measured that exceeds product’s max rating. Investigate cause and power cycle to resume operation in standby.
- Power measured that exceeds product’s internal resistive elements’ max rating. Investigate cause and power cycle to resume operation in standby.
- Resistive elements have exceeded their max temperature rating. Verify adequate cooling air flow and ambient temperature is within product specifications. Power cycle to resume operation in Standby.
- Linear elements have exceeded their max temperature rating. Verify adequate cooling air flow and ambient temperature is within product specifications. Power cycle to resume operation in Standby.
4.10. Factory Restore¶
The ARx Series MagnaLOAD DC electronic load contains EEPROM (electrical erasable programmable read-only memory) for retaining settings after loss of AC power. The memory contains the set points, control mode, calibration gains, offsets, product serial numbers, and more. Most the memory positions are visible using MagnaWEB under the “EEPROM Editor” side menu.
Factory Restore overwrites existing EEPROM settings with defaults values so the MagnaLOAD electronic load can return to a known operating state. This should be performed if user experiences unexpected behavior, due to unknown or forgotten configurations. Magna-Power Electronics may request users perform factory restore, as a starting point in most support cases. The memory positions affected by factory restore are listed in the table below.
Factory restore values (defaults) can be stored in Flash or EEPROM memory, as determined by Magna-Power Electronics. The Flash values are used for product-wide settings, such as control mode and slew rates, and mostly affect the products operating state. EEPROM values are reserved for customer and unit-specific settings, such as gains, offsets, and MagnaLINK™ address information, which are set during factory testing.
Product can be restored to a known state, by modifying the EEPROM in bulk, using either Soft Restore or Hard Restore. Soft Restore only effects those EEPROM positions whose default values are stored in Flash, as shown in the table below. Hard Restore overwrites calibrations values, feedback gains, i.e., settings saved in EEPROM at the factory. In most cases, Soft Restore should be used, and Hard Restore used as a last resort, since it overwrites any in-house calibrations with or original (older) factory calibrations.
Factory restore can be initiated using the front panel by navigating to System Settings - Factory Restore in the menu system. After the restore option has been selected, MagnaLOAD electronic load will reboot and start up with the new settings.
Factory Restore Values
| Name | Memory Type | Restore Value | Description |
|---|---|---|---|
| setPointReg0 | flash | 0 | Current setpoint (normalized) |
| setPointReg1 | flash | 0 | Voltage setpoint (normalized) |
| setPointReg2 | flash | 0 | Power setpoint (normalized) |
| setPointReg3 | flash | 0 | Resistance setpoint (normalized) |
| setPointReg4 | flash | 0 | Rheostat setpoint (normalized) |
| tripOverVoltage | flash | 1.1 | Over Voltage Trip (normalized) |
| tripUnderVoltage | flash | 0 | Under Voltage Trip (normalized) |
| tripDelayVoltage | flash | 0 | Delay Voltage Trip (milliseconds) |
| tripOverCurrent | flash | 1.1 | Over Current Trip (normalized) |
| tripUnderCurrent | flash | 0 | Under Current Trip (normalized) |
| tripDelayCurrent | flash | 0 | Current Trip Delay (milliseconds) |
| tripOverPower | flash | 1.1 | Over Power Trip (normalized) |
| tripUnderPower | flash | 0 | Under Power Trip (normalized) |
| tripDelayPower | flash | 0 | Power Trip Delay (milliseconds) |
| tripOverResistance | flash | 0 | Over Resistance Trip (normalized) |
| tripUnderResistance | flash | 0 | Under Resistance Trip (normalized) |
| tripDelayResistance | flash | 0 | Resistance Trip Delay (milliseconds) |
| setpointSelect | flash | 1 | Last setpoint selected by user |
| controlMode | flash | 1 | Regulation control mode |
| range | flash | 0 | Power range, controls behavior of bypassing resistor modules (LowPower:0, HighPower:1) |
| idxHighSpeedAI | flash | 0 | Selection index that chooses which setpoint, high-speed analog-in signal is applied to. |
| functionType | flash | 0 | Function Type Selection. See EnumFunctionType for more details |
| funcSineAmpl | flash | 0.1 | Sine Fucntion Amplitutde (normalized), applies to Current setpoint. |
| funcSineOffset | flash | 0.5 | Sine Function Offset (normalized), applies to Current setpoint. |
| funcSinePrd | flash | 10 | Sine Function Period in milliseconds |
| funcSqLoLevel | flash | 0.1 | Square Fucntion Low Level (normalized), applies to Current setpoint. |
| funcSqHiLevel | flash | 0.5 | Square Function High Level (normalized), applies to Current setpoint. |
| funcSqLoPrd | flash | 10 | Square Function Low Period in milliseconds |
| funcSqHiPrd | flash | 10 | Square Function High Period in milliseconds |
| funcStepLoLevel | flash | 0.1 | Step Function Low Level (normalized), applies to Current setpoint. |
| funcStepHiLevel | flash | 0.5 | Step Function High Level (normalized), applies to Current setpoint. |
| funcRampLoLevel | flash | 0.1 | Ramp Function Low Level (normalized), applies to Current setpoint. |
| funcRampHiLevel | flash | 0.5 | Ramp Function High Level (normalized), applies to Current setpoint. |
| funcRampRisePrd | flash | 10 | Ramp Function Rise Period in milliseconds |
| funcRampFallPrd | flash | 10 | Ramp Function Fall Period in milliseconds |
| setSource | flash | 0 | Select Setpoint Source from Local, Function or External Ctrl |
| senseMode | eeprom | factory determined | Voltage terminals measurements sourced from local sense (0) or remote sense (1) or leadless sense(2) |
| name | eeprom | factory determined | User assigned name for unit |
| tapSetting | eeprom | factory determined | Amount of digital filtering for voltage and current. Restricted between 0 (no filtering-fast) to 30 (full filtering-slow) |
| ctrlModeAuxPwr | eeprom | factory determined | Control modes for auxiliary power supply. |
| productModelNum | eeprom | factory determined | Product model number (e.g., ARx7.5-1000-15) |
| productType | eeprom | factory determined | Product type (e.g., ARx, ALx, WRx) |
| frontPanelAddr | eeprom | factory determined | Front panel target address (MagnaLINK) |
| frontPanelSeriesNum | eeprom | factory determined | Front panel series number |
| frontPanelSerialNum | eeprom | factory determined | Front panel serial number, Zero if C-Panel |
| ratedVoltTarget | eeprom | factory determined | Maximum voltage (V) target is specified to operate at |
| ratedCurrTarget | eeprom | factory determined | Maximum current (A) target is specified to operate at |
| ratedResTarget | eeprom | factory determined | Maximum resistance (ohm) target is specified to operate at |
| ratedPwrTarget | eeprom | factory determined | Maximum power (W) target is specified to operate at |
| ratedInputVoltTarget | eeprom | factory determined | Maximum line-to-line input voltage (Vrms) product is specified to operate at |
| ratedInputCurrTarget | eeprom | factory determined | Maximum input current (Arms) product is specified to operate at |
| ratedVTermSensor | eeprom | factory determined | Rating for the terminal voltage sensor (V) |
| ratedITermSensor | eeprom | factory determined | Rating for the terminal current sensor (A) |
| ratedVDcLinkSensor | eeprom | factory determined | Rating for the dc link voltage sensor (V) |
| ratedILSensor | eeprom | factory determined | Rating for the phase current sensors (A) |
| gainP1AutoX | eeprom | factory determined | Autocrossover compensator proportional gain1 |
| gainI1AutoX | eeprom | factory determined | Autocrossover compensator integral gain1 |
| gainP2AutoX | eeprom | factory determined | Autocrossover compensator proportional gain1 |
| gainI2AutoX | eeprom | factory determined | Autocrossover compensator integral gain2 |
| gainPModeIPV | eeprom | factory determined | IPV compensator proportional gain1 |
| gainIModeIPV | eeprom | factory determined | IPV compensator integral gain1 |
| gainPModeVPI | eeprom | factory determined | VPI compensator proportional gain1 |
| gainIModeVPI | eeprom | factory determined | VPI compensator integral gain1 |
| gainPModeRPIV | eeprom | factory determined | RPIV compensator proportional gain1 |
| gainIModeRPIV | eeprom | factory determined | RPIV compensator integral gain1 |
| gainPModePIV | eeprom | factory determined | PIV compensator proportional gain1 |
| gainIModePIV | eeprom | factory determined | PIV compensator integral gain1 |
| gainPModeShuntReg | eeprom | factory determined | Shunt regulator compensator proportional gain1 |
| gainIModeShuntReg | eeprom | factory determined | Shunt regulator compensator integral gain1 |
| gainBModeShuntReg | eeprom | factory determined | Shunt regulator compensator band |
| gainCalibrate | eeprom | factory determined | Calibration gains for voltage, current, remote sense voltage, phase current |
| gainCalibrateCtrl | eeprom | factory determined | Calibration gains for set point pwm, capture pwm, available, available, available |
| offset0 | eeprom | factory determined | Protection sensor offset |
| offset1 | eeprom | factory determined | Terminal voltage sensor offset |
| offset2 | eeprom | factory determined | Terminal remote voltage sensor offset |
| offset3 | eeprom | factory determined | Terminal current sensor offset |
| offset4 | eeprom | factory determined | Phase current 1 sensor offset |
| offset5 | eeprom | factory determined | Phase current 2 sensor offset |
| offset6 | eeprom | factory determined | Phase current 3 sensor offset |
| offset7 | eeprom | factory determined | Linear module temperature sensor offset |
| offset8 | eeprom | factory determined | Resistor module 1 temperature sensor offset |
| offset9 | eeprom | factory determined | Resistor module 2 temperature sensor offset |
| offset10 | eeprom | factory determined | External analog set point |
| offset11 | eeprom | factory determined | Internal ADC offset Main Control |
| offset12 | eeprom | factory determined | Internal ADC offset Gate Drive |
| offset13 | eeprom | factory determined | Internal ADC offset Auxiliary Power |
| offset14 | eeprom | factory determined | Slave control PWM offset |
| availAddrLocal | eeprom | factory determined | Address of devices on local network (port A) |
| commOption | eeprom | factory determined | Communication daughter board type |
| ratedVoltProduct | eeprom | factory determined | Maximum voltage (V) product is specified to operate at |
| ratedCurrProduct | eeprom | factory determined | Maximum current (A) product is specified to operate at |
| ratedResProduct | eeprom | factory determined | Maximum resistance (A) product is specified to operate at |
| ratedPowerProduct | eeprom | factory determined | Maximum power (A) product is specified to operate at |
| magnaRouter | eeprom | factory determined | Enable MagnaLINK Interface Device |
| enPortSerialCheck | eeprom | factory determined | Set to enable serialized messages on any port |
| factoryValueSet | eeprom | factory determined | Set to EEPROM to factory calibration mode (disk zero) |
| factoryRestoreMode | eeprom | factory determined | Restore factory defaults to current disk |
| optionRegister | eeprom | factory determined | Integrated Options available on a product |