jjwitty
Member
- Location
- Indianapolis
- Occupation
- Automation
I manage controls in my plant and we hired local electricians to do a project for us.
The project consists of 3 sections of heat tape that heat piping to move oil from a tanker to storage. We need the oil to be around 110 degrees to move around, but I can’t let it go beyond 140 degrees or the chemistry starts breaking down.
I will preface this with the fact the electricians ran the power for the heat tape (220) to one location that’s about 400’ from the pipe inlet. I did show them a location for 220 where the piping begins, but for whatever reason the didn’t tap off of it. Unfortunately there was no formal scope, so I had to work with what they ran. There are three sections of heat tape, two of them are daisy chained.
To control this I bought 3 Solo 4848 ( Manual ) process controllers. I am running a VFD through one controller, and heat tape through the other two ( Rough Sketch ).
Controller 1
Powerflex 525 may not be allowed to start unless the temperature setpoint is met. RTD run = 50’ (outdoors).
Controller 2
L1 of heat tape runs through a NC contact on the controller. This controllers sensor will be close to the sensor that controls the PF525. If the temperature exceeds 140’, the heat tape will lose L1 - power is cut to heat tape - which will also prevent PF525 from starting if conditions aren’t met. RTD = 400’ (outdoors)
Controller 3
L1 of heat tape runs through NC contact on controller. This controller is indoors, and will cut power to the last section of heat tape. RTD=50’ (indoors).
What I’m afraid of is signal loss with the long run of RTD wire that goes outside. Am I right to be concerned? Is there anything I can do to avoid signal loss?
The project consists of 3 sections of heat tape that heat piping to move oil from a tanker to storage. We need the oil to be around 110 degrees to move around, but I can’t let it go beyond 140 degrees or the chemistry starts breaking down.
I will preface this with the fact the electricians ran the power for the heat tape (220) to one location that’s about 400’ from the pipe inlet. I did show them a location for 220 where the piping begins, but for whatever reason the didn’t tap off of it. Unfortunately there was no formal scope, so I had to work with what they ran. There are three sections of heat tape, two of them are daisy chained.
To control this I bought 3 Solo 4848 ( Manual ) process controllers. I am running a VFD through one controller, and heat tape through the other two ( Rough Sketch ).
Controller 1
Powerflex 525 may not be allowed to start unless the temperature setpoint is met. RTD run = 50’ (outdoors).
Controller 2
L1 of heat tape runs through a NC contact on the controller. This controllers sensor will be close to the sensor that controls the PF525. If the temperature exceeds 140’, the heat tape will lose L1 - power is cut to heat tape - which will also prevent PF525 from starting if conditions aren’t met. RTD = 400’ (outdoors)
Controller 3
L1 of heat tape runs through NC contact on controller. This controller is indoors, and will cut power to the last section of heat tape. RTD=50’ (indoors).
What I’m afraid of is signal loss with the long run of RTD wire that goes outside. Am I right to be concerned? Is there anything I can do to avoid signal loss?
