IMO DC Isolator Modular DC Switch 600V 25a 4 pole (double string)

Product Code: 2004

Note: Isolator Only. Our IP66 DC Isolator Enclosure with Opaque Lid, Labelled "Solar DC Isolator" is a great option for this isolator.

Why use an IMO Solar Isolator?

Over 2 million sold worldwide with zero failures, IMO’s TRUE DC Isolators offer unrivaled safety for your Photovoltaic installation.

IMO Precision Controls offers a range of True DC Isolators specifically designed for use in Solar PV installations in accordance with EN 60364-7-712. The IMO design incorporates a user independent switching action so as the handle is moved it interacts with a spring mechanism which, upon reaching a set point, causes the contacts to “SNAP” over thereby ensuring a very fast break/make action. This mechanism means that the disconnection of the load circuits and suppression of the arc, produced by a constant DC load, is normally extinguished in a maximum of 5ms using the specific pole suppression chambers incorporated within the design.

Many alternative solutions, particularly those based upon an AC isolator designs which use bridge contacts, have been modified and rated for DC operation. These types of product have a switching speed that is directly linked to operator speed therefore, slow operation of the handle results in slow contact separation of the contacts which can produce arcing times of 100ms or more. Also in these switches the contact surface is also the surface upon which arcs tend to form; therefore, any surface damage or sooting caused by the arcing is likely to have a detrimental effect on the isolator’s contact resistance and its longevity.

The IMO DC Isolator range is offered in a number of configurations all rated for installation and use as switch-disconnects and all with options allowing for “LOCKABLE OFF” operation. Although able to offer the industry standard two position 90° handle operation from LOCKABLE OFF-ON, IMO have also introduced a SAFE-LOCK patented handle that allows for three rotational positions relating to ON-OFF-LOCK. The facility offered by this design gives a LOCK position that is removed from the OFF setting ensuring the handle can be placed in its own unique position when locked. When this design is used within the IMO enclosed Solar Isolators it ensures that engineering access can only be attained to the enclosure when the handle is in the OFF position; whilst the “LOCK” position ensures secure power isolation combined with non-access to the enclosure (when isolator block is secured with supplied screws) and thereby significantly reducing the risks of tampering when maintenance/repair is carried out on equipment in-line after the isolator, SAFE-LOCK. Once any work has been undertaken the locking mechanism can then be removed from the handle and the isolator returned to its normal operational mode.

IMO Solar Isolators use a rotary “knife contact” mechanism so when the unit is operated the handle movement gives a double make/break per contact set. As DC load switching creates arcing the design is such that this only occurs on the corners of the switching parts meaning that the main contact is made on an area where no arcing has occurred. The rotary contact mechanism methodology used in the IMO Solar Isolators means that, when the isolator is operated, a self-cleaning action occurs on the arcing points and contact surfaces thereby producing good high vibration resistant contact integrity, with reduced contact resistance.

This IMO contact system ensures that power loss per pole is kept as low as possible and consistent over the life of the product unlike conventional style isolators where entrapment of contaminants, and then subsequent compression on lateral operation, can lead to variable and increasing contact resistance and hence per pole losses.

As indicated in the section about Utilisation Categories, the IMO product is satisfactory for use in installations classified as either DC-21A, DC-21B or DC-22A, and also suitable for a high number of “off load” operations (without current) and also a high number of operating cycles “on load” (with current). DC-21A = test current of 1,5 x Ith for 300 operating cycles DC-21B = test current of 1,5 x Ith for 1500 operating cycles DC-22B = test current of 4 x Ith for 300 operating cycles.

A further advantage of the IMO contact mechanism is that, in the event of the supply to earth failure, the high short circuit current pulls the contacts together thereby giving a high short circuit withstand current of up to 1700A (product dependent). Currently the upper limit of PV residential installations is 1000V (600V in AU & NZ) however, IMO Solar Isolators already have the capability to operate up to 1500VDC.

Industry Warning - Beware of Substandard DC Isolators  

In the solar industry you get what you pay for.  It is critical that you understand the implications of the products you sell your customers and who you buy your products from. Hundreds of solar businesses in Australia have closed down under the weight of product recalls and manufacturers/wholesalers going out of business. Just as an example, in Australia there are over 100,000 DC isolators in recall, brands such as  PV Power DC isolator, GEN3 and SPM rotary DC isolators, Avanco and NHP. 

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