Shielding and Chamber Testing
Section 900 Content Consideration
The brief description of the services given in the sub section On-Site testing or Survey is limited but should enable the prospective hirer to identify the hire number under which a more detailed description can be found in the catalogue or on the web site. In many of the test services it is difficult for a number of reasons to actually cost the item number precisely, but the listings form a base price. A typical example would be a shielding effectiveness test like (EN50147-1), (Mil.Std.285) or (IEEE-299). The client has to specify in this case how many frequencies points are to be tested also how many test locations around the chamber are to be measured. These factors will determine the overall duration of the test which may run into days resulting in overnight subsistence etc. The distance to the test site has also to be considered. Most test evaluations will require a concise presentable report that contains not only data but the method of test, type and calibration status of the equipment, summaries and recommendations. If you do not require a detailed report but merely a print-out directly from a data table then make this known to the hire staff before receiving a quote. Once we find out exactly what tasks lay ahead we can then prepare an accurate quotation. Always allow for perhaps an extra day in the contract value if it is your intention to attempt fixes whilst we are on site.
Another service offered is that of a Normalised Site Attenuation test (NSA) which can be done in a chamber (Free Space) or on an open area test site at either 3 or 10 metres. Our NSA software allows for a site verification emulating CISPR-16-4-1 (Swept method of RSM procedure) by periodically verifing our readings using our standard equipment at the country’s National Physics Laboratory Open Area Site at Teddington. Small variations which have crept into the hardware performance are then calculated out in the NSA algorithm to produce a hypothetical zero error. Verification can then be carried out using the CISPR-16 volumetric ten position profile in both H & V at different transmission heights. A single miniature biconical transmit antenna is used from 30MHz to 1GHz emulating an EUT. The whole measurement is swept producing a very accurate high resolution performance status of any test site. A similar service is offered for a fully anechoic chamber (Free Space) where some fifteen points are transmitted from a cylindrical shape emulating large EUTs. This test was earlier referred to as the NSTL measurement.
Finally, all chambers used to measure radiated immunity should meet the requirements of EN61000-4-3 regarding field uniformity as measured from a sixteen point square grid. This service can be offered using our software and facilities. Full reports are issued in all cases.
In the sub section Hire of 5305 G-TEM Cell (on Customer’s Site) there is much to consider and inform us about. Basically, we will be loading the 5305 GTEM into a tail-lift van. Two of our staff will travel to the customer’s premises to facilitate unloading but we will still require the help of one or two personnel from the company hiring to oversee the safe installation of the GTEM into its intended place of operation. With the GTEM you will have already decided on the type of tests you wish to perform, i.e. emissions, immunity or both and that will include the actual test equipment to carry out these two tasks. Concerning the immunity, the many pieces of equipment supplied will include an RF amplifier sufficient to provide at least 15v/m modulated within the cell. If you require larger fields or any other extensions then inform us for a specified quotation. On the emission task there is the choice of either a receiver or spectrum analyzer. If you intend to supply some items of test gear yourself there may be a problem of driver compatibility with our software. Within the model 5305 GTEM, the EUT size should not exceed approx 160mm cubed. Access to the EUT for power & other I/O lines is facilitated via an access panel mounted on the base floor of the GTEM with a waveguide beyond cut-off having a 29mm internal diameter plus a 25 way “D” filtered connector. The hire manager will want to know as much as possible about your situation to help prepare the GTEM plus ancillary equipment prior to delivery. For example, if the EUT needs observing during an immunity test then a special fibrescope camera & light source can be found under item 681.The 5305GTEM Cell can also be hired and used on the premises at EMC Hire in Shefford. A daily or hourly rate will then apply depending on the extra peripheral gear needed
Sub section Field Monitoring Stations (Item 940/941) provides magnetic or electric field monitoring unit under PC operation. Essentially the apparatus is contained within a portable case with a mains wander lead to power up the system. Once initiated on the PC the device can remain monitoring & unattended for twenty four hours or so. Finally, the Conducted Immunity Group (Items 950-958) provides the hirer with a suite of equipment to perform conducted immunity right down to the cables. This can be particularly helpful if the end user is not too familiar with the test. Choices are made between using CDNs or a clamp or using the BCI method. Again, we are available to help you in the choice of system. An engineer can be available to set up the test on behalf of the customer & remain if necessary.