IMO Technical Brochure

8 www.imopc.com + [e-mail] ( 01707 414 444
6
It is because of this that the IMO Solar Isolator range is constructed of materials that signicantly reduce the risk of a re hazard and in
particular our enclosed installation style products for which the main plastic enclosure is rated at UL 94V-0 and the handles are UL 94V-2
rated. The classication criteria for each of these ratings is found in of the UL 94 Table 8.1 (see extract below).
The installation requirements and environments of PV systems can vary signicantly and the IMO Solar Isolator has been designed
such that it can offer a wide range of congurations depending upon the users’ requirement. Also the IMO Solar Isolator range includes
models that, when mounted in accordance with their respective instructions and with the appropriate IMO handle, offer suitable
protection up to IP66 (EN 60529) and NEMA 4X (Nema 250, UL508).
With the advent of more worldwide installations and the requirements laid down in many country’s national wiring publications for the use
of DC switches in PV installations, the IMO Solar Isolators have also been assessed and tested under the latest UL standard UL508i which
has been specically written to cover the use of “Manual Disconnect Switches intended for use in Photovoltaic Systems”.
This UL508i standard specically covers switches rated up to 1500 V that are intended for use in an ambient temperatures of -20
°
C to
+50
°
C, and that are suitable for use on the load side of PV branch protection devices. In order to comply with this standard the IMO DC
Isolators has to pass an overload test, at +50
°
C, of 50 cycles at 200% of rated current; followed by an endurance test of 6000 cycles (6
cycles/min) at rated load (Ith) and a further 4000 cycles with no current.
The IMO DC Isolator has successfully attained certication under the UL508i standard and as such is suitable for use as a disconnection
method for the isolation of the output of DC PV array where it is to be connected to a DC/AC inverter.
Criteria conditions V-0 V-1 V-2
Afterame time for each individual specimen t1 or t2
<10s <10s <30s
Total afterame time for any condition set (t1 plus t2 for the 5 specimens
<50s <250s <250s
Afterame puts afterglow time for each individual specimen after the second ame application (t2+t3)
<30s <60s <60s
Afterame or afterglow of any specimen up to the holding clamp No No No
Cotton indicator ignited by aming particles or drops No No Yes
Examples of Typical PV Installations
Single String System – 3kW Output Single Phase
Consider two potential congurations for a typical 3kW system which would supply 13A at 230VAC:
Inverter: Input: 600VDC (V
OC
), 16A (I
DC
), 32A (I
DC max
) Output: 230VAC (V
AC
), 13A (I
AC
), 17.2A (I
AC max
)
Solar Panel: 60V (V
OC
), 8A (I
SC
) No. of panels: 8
Calculation: V = 8 x 60 x 1.15 = 552V I = 8 x 1.25 = 10A
For this conguration, the IMO SI16-PEL64R-2 rated at 16A for 700VDC is suitable for the DC switch and the PE69-3020 rated at 20A is
suitable for the AC switch.
Inverter: Input: 750VDC (V
OC
), 15A (I
DC
), 28A (I
DC max
) Output: 230VAC (V
AC
), 13A (I
AC
), 16A (I
AC max
)
Solar Panel: 60V (V
OC
), 8A (I
SC
) No. of panels: 10
Calculation: V = 10 x 60 x 1.15 = 895.62V I = 8 x 1.25 = 10A
For this conguration, the IMO SI25-PEL64R-2 would still be suitable as it is rated at 16A for 800VDC, however the IMO SI25-PEL64R-2
rated at 16A for 900VDC would allow for a greater margin of safety. The PE69-3020 rated at 20A is suitable for the AC switch.
L
N
E
Existing AC
Equipment
DC Isolator Inverter AC Isolator
600V: SI16-PEL64R-2 3kW PE69-3020
750V: SI25-PEL64R-2 PE69-3020
PV Arrays
+ + + +
- - - -
+ + + +
- - - -
L
N
E