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Switching time of bypass contactor

Created by: TDzodzo at: 5/28/2014 12:24 PM (19 Replies)

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5/29/2014 12:47 PM	Rate (0)
umencho Grandmaster Joined: 3/21/2006 Last visit: 1/10/2026 Posts: 10247 Rating: (1183)	Let's hope we are talking for the same type of contactor.

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5/29/2014 1:34 PM	Rate (0)
Valli Posts: 262 Rating: (45)	Hope we are talking about 3RW40/ 44
Valli Posts: 262 Rating: (45)
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5/29/2014 1:40 PM	Rate (0)
TDzodzo Posts: 8 Rating: (0)	I was talking about integrated bypass contactor in soft starter, 3RW40/44..
TDzodzo Posts: 8 Rating: (0)
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5/30/2014 3:17 AM
@nkur Posts: 202 Rating: (16)	TDzodzo Dear colleagues, Do you know what is the time required for switching the integrated bypass contactor once the starting time is over? Or it is depenent on particular application you have? Many thanks in advance. HI Can anyone explain what is integrated bypass contactor what are it applications,if any data available??
@nkur Posts: 202 Rating: (16)
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5/30/2014 5:42 AM	Rate (0)
kriipc Silver Member Joined: 4/11/2011 Last visit: 7/11/2025 Posts: 132 Rating: (7)	TDzodzo Dear colleagues, Do you know what is the time required for switching the integrated bypass contactor once the starting time is over? Or it is depenent on particular application you have? Many thanks in advance. May be in this text is some kind of answer. 3RW44 Manual The soft starter features an internal run-up recognition. If a completed motor runup is recognized by the device, the internal bypass contacts close and the thyristors are bridged. If this run-up recognition is performed before the set runup time is completed, the ramp is aborted and the motor voltage is immediately increased to 100 % of the line voltage before the internal bypass contacts are closed. Soft starter desides when is the right time to close contacts. It is irrelevant to know time between "recognition" and physical contact. Voltage is 100% before and after bridging. But I still want to know why this question was asked.
	Last edited by: kriipc at: 5/30/2014 5:50 AM I'm just a human. Mistakes are allowed. Sorry for my english. Only 3 months of training and manuals :)
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5/30/2014 5:43 AM	Rate (0)
Valli Posts: 262 Rating: (45)	Yeap.... 3RW40/ 44 of softstarters are meant to provide smooth start/ Stop of the induction motor. Once, the start/ ramp up time gets over, there is no use of thyristors in the circuit, 3RW has unquie inbuilt by pass contacts system ( inside softstarter) which comes into the picture and power flow happens thru them. Due to this Softstater's thyristor life increases and hence, complete life cycle of Softstarter... You can download its manual for complete understanding... https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=3RW4422-1BC34&caller=view
Valli Posts: 262 Rating: (45)	Last edited by: Valli at: 5/30/2014 5:44 AM
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5/30/2014 5:48 AM	Rate (0)
kriipc Silver Member Joined: 4/11/2011 Last visit: 7/11/2025 Posts: 132 Rating: (7)	UMENCHO To continue the thread - what kind of symptoms are visible if time is too short or too long? How to to be sure the time is configured correctly? Best regads, Hristo Mihalev For "too short" 3RW40/44 3RW44 Manual The "Maximum starting time" parameter can be used to determine the time after which the drive must have completed its run-up. If the drive is not in nominal operation upon completion of the set time, the starting procedure is aborted and an error message is generated. For "too short" 3RW30 3RW30 Manual When using the 3RW30: Make sure the selected ramp time is longer than the actual motor ramp-up time. If not, the SIRIUS 3RW30 may be damaged because the internal bypass contacts close when the set ramp time elapses. If the motor has not finished starting up, an AC3 current that could damage the bypass contact system will flow. For "too long" read answer in previous post. RFM
	Last edited by: kriipc at: 5/30/2014 6:01 AM I'm just a human. Mistakes are allowed. Sorry for my english. Only 3 months of training and manuals :)
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5/30/2014 6:14 AM	Rate (0)
K C Das Posts: 114 Rating: (12)	~~~~Bypass CONTACTOR opens when the motor reaches full speed to reduce power (heat) losses in the solid-state power section. This translates to much smaller enclosures without need for special cooling. Also, the bypass contactor is internal to the soft starter, eliminating the need for additional devices, further reducing enclosure sizes and minimizing installation time. By-pass contactor significantly reduces heat generated by the starter, which minimizes enclosure sizes and costs. With ramp start (the most commonly used form of soft start), the motor is accelerated using an initial torque value of 10 to 85 percent of locked rotor torque, corresponding to 10 to 92 percent of the motor’s locked rotor current. Motor voltage then increases over the ramp time; at 90 percent of rated speed the built-in bypass contractor closes which reduces voltage drop and cuts heat build up in the starter. *The soft start motor accelerator is an electronic, self-contained, panel-or enclosure-mounted motor starting device. It is intended to provide three-phase induction motors with a smooth start, both mechanically and electrically. Soft starters utilize thyristors in a full-wave power bridge confi guration. By varying the thyristor conduction period, the starter controls the voltage applied to the motor. This, in turn, controls the torque developed by the motor. After the motor reaches its designed speed, contacts are closed to bypass the thyristors ~~~~~~~~~~~~ So u hv to monitor or need to know wt time it will take i hope it must b in between 10 to 15 sec ~~~~ I hope it may help u http://image.sciencenet.cn/olddata/kexue.com.cn/bbs/upload/15714Calculating%20Motor%20Start%20Time.pdf
K C Das Posts: 114 Rating: (12)	Last edited by: K C Das at: 5/30/2014 6:51 AM
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5/30/2014 10:49 AM	Rate (0)
metwally mustafa Silver Member Joined: 10/10/2010 Last visit: 7/5/2025 Posts: 309 Rating: (15)	there are some types of soft starters used bypass contactor externally

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6/1/2014 8:53 PM	Rate (0)
aakash parashar Posts: 28 Rating: (4)	Thank you for your answer, Aakash, but I must be more precise. My question was what is the time needed for contact to switch (in miliseconds), when starting time is finished, not what is required setting the starting time. I hope you can provide me this info. HI the soft starter bypass contactor switch on as soon as soft starter NO contact changes through these NO contact coil supply of bypass contactor pick up.if you ask for time... it same as time required by any starter to start a motor after ON PUSH button is pussed.let ln between 1 to 100 ms. regards aakash
aakash parashar Posts: 28 Rating: (4)
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