Digital PLC UV sensors & VIS sensors

The calibration uncertainty stated above is the expanded uncertainty of the calibration (k = 2, confidence level approx. 95 %) and applies to the calibration source and the calibration conditions. In use the measurement uncertainty is larger: spectral mismatch at the source actually used, the sensor temperature, ageing since calibration as well as distance and alignment to the source are added to it. How these combine into an uncertainty budget is explained under Measurement uncertainty in UV measurement.

The PLC.D sends the irradiance reading as an ASCII telegram with a CRC-16 checksum; in addition it transmits serial number, spectral range, calibration date and sensor temperature. The controller can therefore detect whether the connected sensor is the correct one and whether the 12-month calibration interval has been exceeded. The measuring range extends to 10,000 mW/cm², optionally to 10,000 µW/cm² for weak sources.

Via the optional sensor multiplexer up to eight PLC.D sensors can be operated via one RS-485 connection to the PLC and queried individually; the sensors themselves are connected to the multiplexer via RS-232. This is intended for systems with several lamps or web widths, for example dryers with one sensor per lamp. Each sensor keeps its own calibration; the evaluation can compare the values and detect a single declining lamp.

When the controller needs more than a single number: the digital sensor also reports calibration status and temperature, is insensitive to interference on long lines and can be operated via the multiplexer with up to eight sensors on one PLC interface. The analogue PLC sensor with 4–20 mA or 0–10 V remains the simpler solution if a free analogue input is available and only irradiance is monitored. Both measure in the same seven spectral ranges.

The calibration certificate states the expanded calibration uncertainty with k = 2; for the PLC.D sensors it is typically 4.5–6.0 %. In use the measurement uncertainty is larger, because spectral mismatch at the source actually used, sensor temperature, ageing and measuring geometry are added to it. How these combine into an uncertainty budget is explained under Measurement uncertainty in UV measurement.

Permanent monitoring of the lamps with permanently installed UV sensors ensures precise control. This is known as inline monitoring. A dose and irradiance can optionally be calibrated using the curelog or UVpad, which are placed directly on the belt due to their design.

The PLC.D UV sensors are suitable for measuring PWM (pulse width modulation) dimmed LEDs. Internal averaging means that the time average of the irradiance is output precisely. For the same reason, however, individual pulses or flashes cannot be measured.
 

We recommend recalibration every 12 months. To do this, send the PLC.D UV sensors back to us. Ideally, you should obtain a current quotation before returning them to us. Once we have received the order and the PLC.D UV sensor, we can start the recalibration process straight away. We usually need 1 week for factory calibrations and 2-3 weeks for ISO/IEC 17025 calibrations.

Scope of delivery: the PLC.D sensor and the factory calibration certificate. Please state the required spectral range with your order.

The USB version is powered through the USB port and needs no separate power supply.

The multiplexer connects up to eight PLC.D sensors to one machine control: the sensors are attached through RS-232, an RS-485 line runs to the PLC.

For periodic reference measurements the electrically driven shutter protects the sensor from soiling and - at very high irradiance - from ageing.

Accredited calibration to ISO/IEC 17025 in our own calibration laboratory. On delivery the sensor is already factory-calibrated.