Link Microtek

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FAQ's

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What's the difference between ICNIRP, EMF Directive & UK CEMFAW Regulations?

The main  difference is that the ICNIRP (International Commission on Non-Ionizing Radiation Protection) produce guidelines i.e. in themselves they are not legally binding. EMF Directive 2013/35/EU largely incorporates the ICNIRP exposure levels but the difference is that it requires EU member states to have legislation at least meeting the minimum requirements laid down by the Directive. In the UK these are the Control of Electromagnetic Fields Regulations 2016. The exposure levels listed in each document are broadly similar but those that are legally binding obviously take priority so if in any doubt check what applies to you.

Do I need to perform EMF safety measurements?

Sometimes no. You need to perform an EMF risk assessment and if you have EMF workers i.e. those exposed above general public levels in the course of their work then the assessment may get a litle more complicated. If information from equipment manufacturers is available you can just use that for your assessment i.e. no need to do measurements. However if it's difficult to get information or if you have a number of EMF sources grouped together (safety information for equipment will apply in isolation and the total field needs to be considered) then measurements are often the quickest & cheapest means of performing the asessment. Note; when performing your assessment make sure you consider workers at particular risk (see EMF Directive 2013/35/EU & the associated practical guides for details).

How do I choose survey or measurement equipment?

If you need a quantitative reading (rather than an alarm or other indication from a monitor) you need survey equipment. The main considerations are the required frequency range and then the measurement range (the range of field strength values you want to cover). Always check that the specified measurement range covers up to and preferably well beyond the permissible exposure levels e.g. CEMFAW/EMF Directive 2013/35/EU Action Levels or ICNIRP Reference Levels.

What is meant by ‘broadband’ survey equipment?

Generally speaking broadband equipment is designed to measure field strength for comparison with human safety standards or guidelines (hence it is not designed to measure very low field strengths) like EMF Directive 2013/35/EU. It is designed to be isotropic, measure average not peak levels and sum all of the signals or fields that are present within the given frequency range but it does not provide signal frequency information. If you want frequency information you need 'narrow band' or 'frequency selective' equipment.

What is a 'shaped' probe?

A shaped probe measures only in percent of a given exposure level or limit e.g. CEMFAW/EMF Directive 2013/35/EU Action Levels or ICNIRP Reference Levels. The advantage is that you don't need to know the frequency of the field being measured or if multiple signals are present. The probe automatically takes the different level/limit values into account and weights the response accordingly. To summarise it's a a very easy way to perform asessments; the readout is just just a percentage of the Action Level (AL) e.g. 100% represents the AL so lower percentage values indicate compliance.

Why should I use a thermocouple probe for measuring radar signals?

Most probes use diode sensors. If you want to measure a signal that has high peak pulses then the diode can give significant measurement error. It gets a little complicated but ideally a sensor is 'square law' device i.e. it gives a proportional output as input increases. Diode sensors are only 'square law' (often specified as true RMS) over a small part of their measurement range whereas a thermocouple has a true 'square law' response. This means a pulse can drive the diode to where it becomes a peak detector and can provide measurement error wheras the thermocouple will have a true response.

What is meant by narrow band or frequency selective survey equipment?

Narrow band equipment is capable of measuring and analysing different frequencies i.e. the contribution from different signals or frequencies can be assessed in isolation from other signals. Compared to broadband equipment (which usually has a minimum sensitivity of approx 0.3 V/m) it is capable of measuring very low field strengths e.g. microvolts/m. Ask for details of our SRM-3006.

Do I need to measure both the Electric (E) & Magnetic (H) Field?

Generally it is only practical (or necessary) to measure the Magnetic field <300MHz and really becomes more important <100MHz.  At these frequencies it may be necessary to measure both E & H fields close to the source e.g. HF communications or industrial equipment such as 27.12 MHz heat sealers. At much lower frequencies equipment like induction heaters or resistance welders are usually assessed just by considering the magnetic field. At higher frequencies (>300 MHz) it is really only practical to measure the E field.

What’s the difference between monitors and survey equipment?

Monitors are not designed to take measurements, their purpose is to provide an indication when field strength becomes significant with regard to a given permissible exposure level e.g. EMF Directive Action Level or ICNIRP Reference Level.

When should I consider using a personal monitor?

Personal monitors are designed to provide a means of continuous monitoring for an individual. You should consider using a monitor if it is possible for field strength to exceed permissible exposure levels in a working environment. Typical applications are for workers accessing rooftops, masts and towers fitted with telecommunications or broadcast equipment, or defence applications such as radar.

I can’t get my personal monitor to alarm, is it working?

If the unit switches on and goes through its switch on routine it is almost certainly functioning correctly. You need something like a walkie talkie (commercial low cost type) as a check source.  Mobile phones most likely won’t generate enough field strength to cause an alarm.

My personal monitor is set in %, % of what?

It makes sense if a personal monitor has a shaped alarm threshold. This means it alarms at a percentage of a given safety guideline or standard e.g. an alarm at 50% means you have reached 50% of the permissible exposure level. Units for use in the UK and Europe are almost always set to the EMF Directive Action Level.

Can I use a personal monitor set to something other than ICNIRP?

Different countries may have different permissible exposure levels e.g. in the U.S. commonly used exposure levels are those issued by the FCC or IEEE. Whilst broadly similar EMF Directive 2013/35/EU or ICNIRP reference levels are, depending on frequency, lower (more conservative) than the corresponding levels from the FCC or IEEE. This means that different monitors will alarm at different levels. Hence it makes no sense to use non-EMF Directive/ICNIRP units in the UK.

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