Specifications
SPD01 Surge Protection Device :
SPD01
| Surge immunity* | : |
| Surge Immunity (EN-IEC 61000-4-5:2014) | Level 4 |
| Maximum line-to-line surge** | 2 kV, 1 kA |
| Maximum line-to-ground surge** | 4 kV, 2 KA |
| Number of protected instruments | up to 3 |
| Data lines | : |
| Common mode signal voltage range | ± 12 V |
| Differential mode signal voltage range | ± 12 V |
| Maximum line-to-earth voltage | 12 V |
| Mechanical | : |
| Housing material | ASA/PC UL94 V0-1.5mm |
| Cable glands | M12 (protected) |
| Cable diameter | (3 to 6) mm |
| Optional SMF01: rated pole mount diameter | (40 to 60) mm |
| Weight | 0.7 kg |
| DC power lines | : |
| Equipment classification | ± 30 V |
| Maximum DC input current | 5 A |
| Total DC output current | 5 A |
| Rated operating conditions | : |
| Required over-current protection | ≤ 5 A slow blow fuse |
| Rated operating temperature range | (-40 to +80) °C |
| * | tested with all Hukseflux Industrial pyranometers |
| ** | all lines tested as DC power lines |
Downloads
Immunity to high voltages and currents – surges
SPD01 is a surge protection device for digital pyranometers. It is designed for use with the Hukseflux-brand “industrial pyranometer” series of instruments. The device combines and coordinates the protection of the power supply and the RS-485 serial communication lines. Protection of the pyranometer against electrical surges is very important to guarantee reliable operation in harsh “industry grade” outdoor environments such as solar (PV) power plants and meteorological stations. Hukseflux industrial pyranometers are tested and classified for Industrial Environments according to IEC 61326-1 and IEC 61000-6-2.
Why add an SPD?
When designing a measurement system, pyranometer users may attain several levels of immunity. For example, the surge immunity of the SR300-D1 industrial pyranometer is Level 2 (up to 1 kV surges) according to IEC 61000-4-5. Adding the Surge Protection Device SPD01, the immunity is increased to 4 kV.
To attain the required level of immunity for a given installation, some general system components should be included, such as:
• lightning protection system
• earthing and grounding network
• external surge protection in addition to the native on-board sensor protection
SPD01 properties
In the electrically harsh environment of PV power plants, SPD01 protects connected instruments from lightning – and power-switching induced surge events. At the same time, it allows for a flexible system design. Properly installing the SPD01 near a Hukseflux industrial pyranometer, assures that voltages and currents reaching the sensor are strongly suppressed.
System design
Provided that instruments are in close proximity to the SPD, up to 3 instruments can be protected by a single SPD01.
- instruments are protected from surges in the grounding system
- the distance between the instrument and SCADA system may be increased significantly
Depending on the system design and instrument location, multiple SPD01’s may be used.
In some cases, for example on-array installation of pyranometers, it is beneficial to isolate the instruments from the mounting platform. Hukseflux supplies an optional accessory for this, the PID01 Pyranometer Isolation Disc.
Optional SMF01
SMF01 is a practical metal bracket that helps mounting a surge protection device on a vertical mast.
Suggested use
- PV system performance monitoring
- scientific meteorological observations
Areas of Application
How does a pyranometer work?
A pyranometer measures the solar radiation received by a plane surface from a 180 ° field of view angle. This quantity, expressed in W/m², is called “hemispherical” solar radiation. The solar radiation spectrum extends roughly from 285 to 3000 x 10⁻⁹ m. By definition a pyranometer should cover that spectral range with a spectral selectivity that is as “flat” as possible.
In an irradiance measurement by definition the response to “beam” radiation varies with the cosine of the angle of incidence; i.e. it should have full response when the solar radiation hits the sensor perpendicularly (normal to the surface, sun at zenith, 0 ° angle of incidence), zero response when the sun is at the horizon (90 ° angle of incidence, 90 ° zenith angle), and 50 % of full response at 60 ° angle of incidence. A pyranometer should have a so-called “directional response” (older documents mention “cosine response”) that is as close as possible to the ideal cosine characteristic.
In order to attain the proper directional and spectral characteristics, a pyranometer’s main components are:
• a thermal sensor with black coating. It has a flat spectrum covering the 200 to 50000 x 10⁻⁹ m range, and has a near-perfect directional response. The coating absorbs all solar radiation and, at the moment of absorption, converts it to heat. The heat flows through the sensor to the sensor body. The thermopile sensor generates a voltage output signal that is proportional to the solar irradiance.
• a glass dome. This dome limits the spectral range from 285 to 3000 x 10⁻⁹ m (cutting off the part above 3000 x 10⁻⁹ m), while preserving the 180 ° field of view angle. Another function of the dome is that it shields the thermopile sensor from the environment (convection, rain).
• a second (inner) glass dome: For secondary standard and first class pyranometers, two domes are used, and not one single dome. This construction provides an additional “radiation shield”, resulting in a better thermal equilibrium between the sensor and inner dome, compared to using a single dome. The effect of having a second dome is a strong reduction of instrument offsets.
• a heater: in order to reduce the effect of dew deposition and frost on the outer dome surface, most advanced pyranometers have a built-in heater. The heater is coupled to the sensor body. Heating a pyranometer can generate additional irradiance offset signals, therefore it is recommended to activate the heater only during night-time. Combining a heater with external ventilation makes these heating offsets very low.
Why use a pyranometer?
There are good reasons why pyranometers are the standard for solar radiation measurement in outdoor PV system performance monitoring.
The purpose of outdoor PV testing is to compare the available resource to system output and thus to determine efficiency. The efficiency estimate serves as an indication of overall performance and stability. It also serves as a reference for remote diagnostics and need for servicing.
The irradiance measurement for outdoor PV performance monitoring is usually carried out with pyranometers. Some standards suggest using PV reference cells. Reference cells are (with some minor exceptions) unsuitable for proof in bankability and in proof of PV system efficiency. Pyranometers are and will remain the standard for outdoor solar energy monitoring.
From a fundamental point of view:
- Pyranometers measure truly available solar irradiance (so the amount of available resource). This is the parameter you need to have for a true efficiency calculation.
- Reference cells measure only that part of solar radiation that can be used by cells of identical material and identical packaging (flat window), so the yield of a certain PV cell type. This is not a measurement that can be used in an efficiency calculation and in fact leads to several percentage points error in efficiency estimates.
The International Energy Agency (IEA) and ASTM standards for PV monitoring recommend pyranometers for outdoor PV monitoring. PV reference cells do not meet IEC 61724-1 class A requirements for irradiance measurement uncertainty: their directional response makes them systematically overestimate daily radiant exposure in J/m2 (or W·hr/m2 ) by more than 2 %, larger on hourly basis.
How do I choose a pyranometer?
- are there standards for my application?
- what level of accuracy do I need?
- what will be the instrument maintenance level?
- what are the interfacing possibilities?
- recommended pyranometer class
- recommended maintenance level
- estimate of the measurement accuracy
- recommended calibration policy
- recommended interface
What is the difference between a pyrheliometer and a pyranometer?
A pyranometer measures hemispherical solar radiation. When measuring in the horizontal plane this is called Global Horizontal Irradiance (GHI). When measuring in “plane of array”, next to PV panels, this is called plane of array POA irradiance.
A pyrheliometer is used to measure Direct Normal Irradiance (DNI). DNI is defined as the solar radiant flux collected by a plane unit surface normal to the axis pointing towards the centre of the sun, within an optical angular aperture. DNI is composed of the solar irradiance within the extent of the solar disk (half-angle 0.266 ° ± 1.7 %) plus some circumsolar radiation.
