2. Product Introduction¶
2.1. Key Features¶
The WRx Series MagnaLOAD DC electronic load is available in power levels of 12.5 kW, 25 kW, 50 kW, 75 kW, and 100 kW. The 12.5 kW models come in a 4U rack-mount package, while the 25 kW to 100 kW models come in various stand-alone cabinets. Each power level has three models, with a wide voltage-current operating profile where full power can be achieved. The key features of the MagnaLOAD electronic load are as follows:
Product Features
- MagnaLINK™ distributed DSP architecture
- 16-bit programming and monitoring resolution
- Voltage, current, power, resistance, rheostat, and shunt regulator control modes
- Various diagnostics and protection features, including: over voltage trip, under voltage trip, over current trip, over power trip and over resistance trip.
- Front and rear panel USB (host), RS485, MagnaLINK™ IN and OUT ports
- Configurable 25-pin analog-digital External User I/O port
- Designed and manufactured in the USA
2.2. Models¶
The following tables list the available models in the WRx Series MagnaLOAD DC electronic load.
2.2.1. Model Ordering Guide¶
The following ordering guide defines how an WRx Series MagnaLOAD DC electronic load is defined:
Fig. 2.1 WRx Series MagnaLOAD DC electronic load Model Ordering Guide
2.2.2. WRx Series Models¶
| Model | Maximum Power | Maximum Voltage | Maximum Current | Package Type | Minimum Voltage |
|---|---|---|---|---|---|
| WRx12.5-200-130 | 12.5 kW | 200 Vdc | 130 Adc | Rack-mount | 2.5 Vdc |
| WRx12.5-500-52 | 12.5 kW | 500 Vdc | 52 Adc | Rack-mount | 3.0 Vdc |
| WRx12.5-1000-26 | 12.5 kW | 1000 Vdc | 26 Adc | Rack-mount | 5.0 Vdc |
| WRx25-200-260 | 25 kW | 200 Vdc | 260 Adc | Floor-standing | 2.5 Vdc |
| WRx25-500-104 | 25 kW | 500 Vdc | 104 Adc | Floor-standing | 3.0 Vdc |
| WRx25-1000-52 | 25 kW | 1000 Vdc | 52 Adc | Floor-standing | 5.0 Vdc |
| WRx50-200-520 | 50 kW | 200 Vdc | 520 Adc | Floor-standing | 2.5 Vdc |
| WRx50-500-208 | 50 kW | 500 Vdc | 208 Adc | Floor-standing | 3.0 Vdc |
| WRx50-1000-104 | 50 kW | 1000 Vdc | 104 Adc | Floor-standing | 5.0 Vdc |
| WRx75-200-780 | 75 kW | 200 Vdc | 780 Adc | Floor-standing | 2.5 Vdc |
| WRx75-500-312 | 75 kW | 500 Vdc | 312 Adc | Floor-standing | 3.0 Vdc |
| WRx75-1000-156 | 75 kW | 1000 Vdc | 156 Adc | Floor-standing | 5.0 Vdc |
| WRx100-200-1040 | 100 kW | 200 Vdc | 1040 Adc | Floor-standing | 2.5 Vdc |
| WRx100-500-416 | 100 kW | 500 Vdc | 416 Adc | Floor-standing | 3.0 Vdc |
| WRx100-1000-208 | 100 kW | 1000 Vdc | 208 Adc | Floor-standing | 5.0 Vdc |
2.3. Specifications¶
2.3.1. Power Specifications¶
AC Input Voltage
1Φ, 2-wire + ground
|
85 to 265 Vac (UI: Universal Input); Available on 12.5 kW Models
120 Vac (120SP: operating range 108 to 132 Vac); Available on 25 kW to 100 kW Models
208 Vac (208SP: operating range 187 to 229 Vac); Available on 25 kW to 100 kW Models
240 Vac (240SP: operating range 216 to 264 Vac); Available on 25 kW to 100 kW Models
|
| AC Input Frequency | 45-66 Hz |
| AC Input Isolation | ±1500 Vac, maximum AC input voltage to ground |
| DC Input Isolation | ±1500 Vdc, maximum DC input voltage to ground |
2.3.2. Programming Specifications¶
| Resolution (All Modes) | 16-bit, 0.0015% |
| Accuracy | Voltage: ±0.1% of full scale voltage rating
Current: ±0.2% of full scale current rating
Power: ±0.3% of full scale power rating
Resistance: ±0.3% of full scale resistance rating
|
| Rise/Fall Time, Maximum | Voltage Mode: 100 ms, 10% to 90% max voltage
Current Mode: 2 ms, 10% to 90% max current
Power Mode: 100 ms, 10% to 90% max power
Resistance Mode: 40 ms, 10% to 90% max resistance
|
| Trip Settings Range | Over Voltage: 10% to 110% of max voltage rating
Under Voltage: 0% to 110% of max voltage rating
Over Current: 10% to 110% of max current rating
Over Power: 10% to 110% of max power rating
|
2.3.3. Connectivity Specifications¶
| Communication Interfaces (Standard) | USB Host (Front): Type B
USB Host (Rear): Type B
RS485 (Rear): RJ-45
MagnaLINK™: RJ-25 x 2
External User I/O: 25-pin D-Sub female
|
| Communication Interfaces (Optional) | LXI TCP/IP Ethernet (Rear): RJ-45
GPIB (Rear): IEEE-488
|
2.3.4. External User I/O Specifications¶
| Digital Inputs | 5 V, 10 kΩ impedance |
| Digital Monitoring Signals | 5 V, 32 mA capacity |
| Digital Reference Signals | 5 V output, 20 mA capacity |
| Analog Sampling Rate | 2 kHz |
| Analog Programming Input | 0-10 V |
| Analog Programming Impedance | 10 kΩ |
| Analog Programming Resolution | 12-bit, 0.025% |
| Analog Monitoring Signals | 0-10 V, 3 mA capacity |
| Analog Monitoring Impedance | 0.005 Ω |
| Analog Monitoring Accuracy | 0.05% of max rating |
| Analog Reference Signal | 10 V, 20 mA capacity |
2.3.5. Physical Specifications¶
| Power Level | Rack Units | Size | Weight |
| 12.5 kW | 4U | 7” H x 24” W x 19” D
(17.8 x 60.9 x 48.2 cm)
|
165 lbs (74.8 kg) |
| 25 kW | 12U Cabinet | 30.7” H x 24” W x 31.5” D
(78.0 x 61.0 x 80.0 cm)
|
455 lbs (206.4 kg) |
| 50 kW | 24U Cabinet | 58.25” H x 24” W x 31.5” D
(148.0 x 61.0 x 80.0 cm)
|
785 lbs (356.1 kg) |
| 75 kW | 24U Cabinet | 58.25” H x 24” W x 31.5” D
(148.0 x 61.0 x 80.0 cm)
|
1115 lbs (505.8 kg) |
| 100 kW | 36U Cabinet | 74” H x 24” W x 31.5” D
(188.0 x 61.0 x 80.0 cm)
|
1445 lbs (655.4 kg) |
2.3.6. Environmental Specifications¶
| Ambient Operating Temperature | 0°C to 50°C |
| Storage Temperature | -25°C to +85°C |
| Humidity | Relative humidity up to 95% non-condensing |
| Air Flow | Front air inlet, rear exhaust |
2.3.7. Water Cooling Specifications¶
| Water Connection Provided | 12.5 kW Models: 1/2” NPT male inlet and outlet
25 kW to 100 kW Models: 1” NPT male inlet and outlet
|
| Maximum Inlet Temperature | 25°C |
| Maximum Inlet Pressure | 80 PSI |
| Minimum Flow Rate | 12.5 kW Models: 1.5 GPM
25 kW Models: 3.0 GPM
50 kW Models: 6.0 GPM
75 kW Models: 9.0 GPM
100 kW Models: 12.0 GPM
|
2.3.8. Regulatory Compliance¶
| EMC | Complies with European EMC Directive for test and measurement products, 2014/30/EU |
| Safety | Complies with EN61010-1:2010-02 |
| CE Mark | Yes |
| RoHS Compliant | Yes |
2.4. Dimensional Diagrams¶
2.4.1. WRx Series - 12.5 kW Models¶
Fig. 2.2 WRx Series 12.5 kW rack-mount models front panel, rear panel, and side panel (top to bottom).
2.4.2. WRx Series - 25 kW to 100 kW Models¶
Fig. 2.3 Front panel dimensions for WRx Series 25 kW to 100 kW floor standing models.
Fig. 2.4 Rear panel dimensions for WRx Series 25 kW to 100 kW floor standing models.
Fig. 2.5 DC output bus dimensions for WRx Series 25 kW to 100 kW floor standing models.
2.5. Options and Accessories¶
The following is a list of integrated options available for the WRx Series MagnaLOAD DC electronic load:
| Name | Option Code | Description |
|---|---|---|
| LXI TCP/IP Ethernet | +LXI | Integrated TCP/IP Ethernet communications port |
| IEEE-488 GPIB | +GPIB | Integrated IEEE-488 GPIB communications port |
| Blank Front Panel | +BP | Front panel providing only control power, status LED, and USB port |
The following is a list of accessories available for the WRx Series MagnaLOAD DC electronic load:
| Name | Description |
|---|---|
| MagnaLINK-6 | 6-ft MagnaLINK Cable |
| MagnaLINK-12 | 12-ft MagnaLINK Cable |
| MID-M | MagnaLINK Interface Device - Master |
| MID-S | MagnaLINK Interface Device - Slave |
| CAB1 | 12U Cabinet, 32” H x 24” W x 31.5” D |
| CAB2 | 24U Cabinet, 51.5” H x 24” W x 31.5” D |
| CAB3 | 30U Cabinet, 67” H x 24” W x 31.5” D |
| CAB4 | 36U Cabinet, 75” H x 24” W x 31.5” D |
| CAB3x2 | 60U Double Cabinet, 67” H x 48” W x 31.5” D |
| CAB4x2 | 72U Double Cabinet, 75” H x 48” W x 31.5” D |
Note
Cabinets are only available for rack-mount MagnaLOAD electronic loads. Floor-standing MagnaLOAD electronic loads come standard integrated into cabinets.
2.6. Principle of Operation¶
Magna-Power Electronics MagnaLOAD DC electronic loads are offered in three variations: the ARx Series, the WRx Series, and the ALx Series. The ARx Series and WRx Series is comprised of a bank of MOSFETs and a series connected array of power resistors configured in a binary format. The ALx Series, which utilizes a more conventional electronic load circuit topology, is comprised simply as a bank of MOSFETs. Both models use three MOSFETs arranged in modular subassemblies called linear modules. These modules contain the necessary drive, feedback, and protection circuitry.
Fig. 2.6 shows a simplified version of the ARx Series and WRx Series, which includes two basic series connected elements: resistor R1 and current source Q1. The current source consists of MOSFET Q1, shunt resistor R2, and operational amplifier U1. Load current, IL, is set with voltage V1 applied to the positive input of operational amplifier U1. V1 drives the gate of Q1 high until the voltage across the shunt resistor, VR2, equals that of V1. The load current, IL, will be equal to V1/R2.
Fig. 2.6 Basic ARx Series and WRx Series MagnaLOAD dissipative component
Assuming the power across the shunt resistor is insignificant, the power dissipated in load resistor R1 is IL x VR1 and the power dissipated in MOSFET Q1 is IL x VQ1. The resistors can be operated at higher temperatures than the MOSFETs, simplifying cooling requirements of the passive elements. Keeping VQ1 small and VR1 large lowers system costs in comparison with purely semiconductor electronic loads. Adjusting the value of resistor R1 is accomplished with a binary switching matrix.
Keeping the resistor switching increments small and over a wide range maintains the smallest voltages across the linear modules and over the widest operating range. The ARx Series and WRx Series has 31 resistor switching states to accomplish this goal. In parallel with the resistors is a shorting switch which provide a very low impedance to bypass the resistor matrix. With the shorting switch enabled, the ARx Series and WRx Series operates like a conventional electronic load and is capable of providing a near zero impedance. The power limit in this mode is that of the linear modules.
With the linear modules fully conducting, the ARx Series and WRx Series can operate solely with the resistor matrix providing 31 resistor states. This mode, called rheostat mode, has no feedback controls for automatic adjustment. Rheostat mode eliminates any possible instabilities between the source and load and is basically a programmable power resistor.
The linear modules have protection circuitry to protect itself from abusive conditions. Each linear module is protected against over current and over voltage conditions. These fault conditions are independent of normal feedback operation. Over current conditions causes shutdown of the system. Over voltage conditions operate in two states. If the voltage applied to the load exceeds it rating, the linear module first acts as a power Zener diode to clamp any transient voltage such as that produced by Ldi/dt. After short instant in time, the ARx series shuts down like over current protection.
The ALx Series uses the same linear modules as the ARx Series. The ALx series has no resistor matrix and no shorting switch. The ALx Series uses 12 linear modules for 2,500 Watt operation, while the ARx Series and WRx Series uses 4 linear modules for 6,750 Watt and 12,500 Watt operation, respectively. The ALx Series has a wider constant power range since there is no restriction with application of the resistor matrix.
The control system has multiple digital signal processors (DSPs), a minimum of 4 are used with others depending on external communications. The combination gives both the ARx and ALx Series powerful control in regulating current, voltage, power, resistance, and rheostat mode. Both the ARx Series and ALx Series use the same control scheme. Like all Magna-Power products, all control circuitry is referenced to earth ground eliminating ground loops between communications equipment.