Electro Pneumatic Positoiner EPL Type

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Anonymous Poster #1	Electro Pneumatic Positoiner EPL Type 08/07/2012 5:34 AM
	Hi The currently I'm using some instrument equipments, and now some control valve " Electro pneumatic positioner EPL type" met trouble as below: Normally the controller working with range (4~20mA DC) same (0~100% opening valve).However recently some of them met trouble that when we input 12mA the controller open 100% of valve and keep therer but as the theory it must open 50% of valve, then we change input pressure it work normally in some hours and then it met trouble again. I saw manual but i don't have any information about that trouble Please support me if you know Thanks CR4 ADMIN - email address removed From the CR4 Rules: Do not post phone numbers or email addresses. The CR4 Admin will delete all phone numbers and email addresses posted in threads or comments. You can share this information via the CR4 internal messaging system.
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Iris Guru Join Date: Jul 2010 Posts: 669 Good Answers: 176	#1 Re: Electro Pneumatic Positoiner EPL Type 08/07/2012 11:10 AM
	In the event of loss of electrical or pneumatic input signal, positioners are designed to have its output go to fail-safe position. I wonder if the move to 100% is a fail-safe response to loss of input signal.
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Join Date: Aug 2012

Posts: 1

#2
In reply to #1

08/08/2012 2:04 AM

Hi Please kindly see the my report for the testing the pneumatic input signal and the position of the positioner Output signal from DCS to Valve ( disconnect DCS output signal cable at positioner (Bzone top A only))

		Butterfly valve B zone top A


		BV 5201
		BV 5201
	MV(%)	openning of valve(%)
	0%	3.908mA
	50%	12mA
	100%	20.998mA

Connect DC signal source/ Output 4-20mA (B zone top A only)

		Butterfly valve B zone top A


		BV 5201
		BV 5201
	4-20mA	openning of valve(%)
	4	0%
	12	50%
	20	100%

However, sometime it met trouble is alway 100% positino although we try to set down

it is not a fail-safety response to loss input signal because when it is met trouble we check mA is Ok( same output from DCS)

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Virgin Mary Member Join Date: Oct 2010 Location: Central Oklahoma, USA Posts: 8	#3 Re: Electro Pneumatic Positoiner EPL Type 08/08/2012 10:57 AM
	We had a similar problem with a Sullivan & Sons Valve Positioner. Make sure the unit has a good ground connection and ground the shield of the 4-20 mA signal at the positioner. (The shield by itself does not provide a good ground to the unit.) vM __________________ "If you can't explain it simply, you don't understand it well enough." (AE)
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