Maker Pro
Maker Pro

intrinsically safe safety 12v

H

HarryHydro

Jan 1, 1970
0
Hi Folks:
I'm hunting for a solution to this problem. I have a 13.2V battery
(charging) in a safe area. This goes through a custom barrier (ISCOM)
to a computer in a hazardous area. There is a new intrinsically safe
solenoid in the hazardous area, but it needs about 10V at 30mA to
switch. The added current would blow the ISCOM, which already doesn't
have the voltage the solenoid needs. The common zener-resistor
barriers I've seen drop too much voltage and we have no 24V that the
active devices require. The best we've come up with so far is 9.6V
that works when the solenoid is warm, but not cold (like today). This
is taking into account the voltage drop in all the wiring as well.
Any ideas apprecieated!
Thanks!
Harry
 
P

Phil Hobbs

Jan 1, 1970
0
HarryHydro said:
Hi Folks:
I'm hunting for a solution to this problem. I have a 13.2V battery
(charging) in a safe area. This goes through a custom barrier (ISCOM)
to a computer in a hazardous area. There is a new intrinsically safe
solenoid in the hazardous area, but it needs about 10V at 30mA to
switch. The added current would blow the ISCOM, which already doesn't
have the voltage the solenoid needs. The common zener-resistor
barriers I've seen drop too much voltage and we have no 24V that the
active devices require. The best we've come up with so far is 9.6V
that works when the solenoid is warm, but not cold (like today). This
is taking into account the voltage drop in all the wiring as well.
Any ideas apprecieated!
Thanks!
Harry

When you say "hazardous area", I assume you mean one that may have an
explosive atmosphere, is that right? And in an industrial setting?

Could you tell us a bit more about the exact requirement?

Cheers,

Phil Hobbs
 
H

Homer J Simpson

Jan 1, 1970
0
HarryHydro said:
Hi Folks:
I'm hunting for a solution to this problem. I have a 13.2V battery
(charging) in a safe area. This goes through a custom barrier (ISCOM)
to a computer in a hazardous area. There is a new intrinsically safe
solenoid in the hazardous area, but it needs about 10V at 30mA to
switch.

Can't you use a pneumatic actuator? Or a mechanical link?
 
Hi Folks:
I'm hunting for a solution to this problem. I have a 13.2V battery
(charging) in a safe area. This goes through a custom barrier (ISCOM)
to a computer in a hazardous area. There is a new intrinsically safe
solenoid in the hazardous area, but it needs about 10V at 30mA to
switch. The added current would blow the ISCOM, which already doesn't
have the voltage the solenoid needs. The common zener-resistor
barriers I've seen drop too much voltage and we have no 24V that the
active devices require. The best we've come up with so far is 9.6V
that works when the solenoid is warm, but not cold (like today). This
is taking into account the voltage drop in all the wiring as well.
Any ideas apprecieated!
Thanks!
Harry

An I.S. DC-DC barrier would be preferable to the somewhat dated Zener
blocks. The input supply voltage feeds 1:1 to the load but is
galvanically isolated and I.S. approved

Pepperl+Fuchs do a whole range of I.S. isolators. Google instantly
turned up ...
http://www.247able.com/mcp/Barriers_Isolators.html
look at the kFD2 solenoid driver range.
Expensive naturally.
john
 
N

nospam

Jan 1, 1970
0
HarryHydro said:
Hi Folks:
I'm hunting for a solution to this problem. I have a 13.2V battery
(charging) in a safe area. This goes through a custom barrier (ISCOM)
to a computer in a hazardous area. There is a new intrinsically safe
solenoid in the hazardous area, but it needs about 10V at 30mA to
switch. The added current would blow the ISCOM, which already doesn't
have the voltage the solenoid needs. The common zener-resistor
barriers I've seen drop too much voltage and we have no 24V that the
active devices require. The best we've come up with so far is 9.6V
that works when the solenoid is warm, but not cold (like today). This
is taking into account the voltage drop in all the wiring as well.

So hang a small dc-dc converter across the battery to get enough voltage to
drive through a conventional barrier?

--
 
H

HarryHydro

Jan 1, 1970
0
HarryHydrowrote:

When you say "hazardous area", I assume you mean one that may have an
explosive atmosphere, is that right? And in an industrial setting?

Could you tell us a bit more about the exact requirement?

Cheers,

Phil Hobbs- Hide quoted text -

- Show quoted text -

Hi: Thanks for the reply. In the safe area we have a 12V battery bank
and charger. There is a custom barrier box for a computer that reside
in the hazardous area. There are pneumatic operators here also . In
an effort to save time and money (hard conduit, etc.), we're using an
intrinsically safe solenoid set. These solenoids need 10V @ 30mA to
switch. The computer provides an open-drain FET for switching. This
may be 12V only, being clamped to the + rail. What we've done is use
another custom barrier for the solenoid, but I think these are
expensive to. Overall, it's still cheaper than re-tubing.
 
Top