Mark at Curtis

[Mark at Curtis]

Hello everyone, this is my first post in the forum although I have been using its help information for quite some time. So here it is,, I have a problem with some 120v, 150w HPS lights. There are eight fixtures in the circuit and I am pulling 30 to 40 amps total measured at the panel. The panel is in a mini load center, single phase 480/240, 120v. Lighting is controlled by a contactor with a photo cell and appears to be working fine. Other than the high amp draw when the contactor opens up in the morning it faults the PLC being fed with a120v circuit out of the same mini load center. The PLC circuit has a Allen Bradley DIN rail surge protector and filter protecting the PLC. Another big kicker is the lights work fine and draw the correct amps when hooked up to and ran off a portable generator in the back of a service truck. The PLC only faults when the lighting contactor opens up in the morning.

Any ideas???

 

[rt66electric]

Hello everyone, this is my first post in the forum although I have been using its help information for quite some time. So here it is,, I have a problem with some 120v, 150w HPS lights. There are eight fixtures in the circuit and I am pulling 30 to 40 amps total measured at the panel. The panel is in a mini load center, single phase 480/240, 120v. Lighting is controlled by a contactor with a photo cell and appears to be working fine. Other than the high amp draw when the contactor opens up in the morning it faults the PLC being fed with a120v circuit out of the same mini load center. The PLC circuit has a Allen Bradley DIN rail surge protector and filter protecting the PLC. Another big kicker is the lights work fine and draw the correct amps when hooked up to and ran off a portable generator in the back of a service truck. The PLC only faults when the lighting contactor opens up in the morning.

Any ideas???

M
might try...
Adding a small style ups strip ahead of the PLC .

I assume 30to40 amp is the total load on the panel?? it is a little high for just 8 lights.

What you are experiencing is not a high amp draw ,but a capacitance or voltage surge/spike... lighting ballasts are transformer or inductive loads. When the load is suddenly turned off, excess amperage is converted into voltage. The length of wire determines the capacitance effect. V=IR I(amps) changes suddenly and the electrons have nowhere to go, and smash into the end of the wire and reverberate back. :slaphead:

Also , make sure that the supply wires and switchlegs are in the same conduit.
If the supply circuit goes in one pipe and switchlegs go out another without a neutral in the pipe, then it causes problems. Search for "Hysteresis effect".

If that does not work, then separate the load between two contactors and put a small "delay-off" relay on one of them.

My guess the problem is the routing of the power and switchleg wires.