PWM signals for governor |
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PWM signals for governor |
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 Jul 29 2006, 02:48 PM
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#1
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 Member  Group: Full Member Posts: 165 Joined: 3-September 04 Member No.: 861  |
Hi !!
We are using Woodard make Load sharing module for our new ( 6th) CAT generator. We notice a speed drop when load is applied. The engine is 45 meter away from this module.( module governs speed based on Load). The manufacturer recommends a max of 30 metres between module and engine. Now, my questions are, 1)Will this distance effect the signal ( PWM) ? We have used screened cable, untwisted cores, and grounded at one end only. 2)Will twisted pair screened cable be better? 3) Is there any attenuator/amplifier availabe for PWM signals which i can install midway to strengthen the speed signal. |
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Aug 15 2006, 08:09 AM
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#2
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Posting Freak Group: Moderator Posts: 2,118 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Hello Chaterpilar
If the output of the controller is a PWM ouptu, it will have a high frequency component. The length of the cable with have an impact on the resistance, inductance and capacitance of the cable. This will have an impact on the result if the resistance and/or inductance of the cable are significant relative to the circuit connected on the output of the cable. The capacitance will have an impact if the output impedance of the PWM circuit is current limited. If the problem is due to the capacitance of the cable, a non screen cable may help to improve the situation, but the capacitance between the cores will still be an issue. Inline amplifiers are possible, but I would need to have a lot of information on the PWM output and the input circuit. Best you ask the agents about this one. Best regards, -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
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Oct 8 2006, 05:43 AM
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#3
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Junior Member Group: Members Posts: 4 Joined: 9-April 06 Member No.: 1,464 |
If your load control module is set to droop mode, then this would be normal operation.
In parallel operation, a problem with the load control module will be a load sharing problem. All generators in parallel will be locked to the same speed. An attenuation problem with the PVM signal to one set will cause that set to take less than it's share of the load, but the parallel connection will not permit one set to run at a lower speed than the other sets. yours |
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Oct 31 2006, 12:52 PM
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#4
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Member Group: Full Member Posts: 165 Joined: 3-September 04 Member No.: 861 |
QUOTE(waross @ Oct 8 2006, 08:43 AM) [snapback]4649[/snapback] If your load control module is set to droop mode, then this would be normal operation. In parallel operation, a problem with the load control module will be a load sharing problem. All generators in parallel will be locked to the same speed. An attenuation problem with the PVM signal to one set will cause that set to take less than it's share of the load, but the parallel connection will not permit one set to run at a lower speed than the other sets. yours Waross, We are using isochronous mode and hence droop is bypassed. The problem was the distance between the synchronising panel and the LSM which as per Woodward cannot be more than 30 metres We relocated the Wood ward LSM and the problem was solved. chaterpilar |
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