[TRNSYS-users] TRNSYS-users Digest, Vol 119, Issue 30

[Jeff Thornton]

You may try using a different controller. The PID controller in the
standard library and one of the n-stage differential controllers in the
TESS Controls Library come to mind. And definitely use smaller timesteps
- we prefer a 1-minute timestep for most applications. 

Jeff 

---
Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577 Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton at tess-inc.com

On 11/26/2014 3:37 pm, bridjesh gautam wrote: 

> Thank you MR. Heymer and Thronton 
> I connected control function directly to Type 46 and worked well but I do have one more question. 
> I am controlling Type 110 pump with Type 22 controller and have noticed pump always starts with a peak of rated volume flow. My pump has minimum flow ,25% of rated mass flow and setting minimum control function to 0.25 or even 0 does not help. 
> I tried changing Threshold for non-zero output and Maximum number of oscillations to various value still having no luck. 
> I read that pump does not model on-off condition does that mean running simulation with very small time steps(>1 min) will have bigger impact on overall result ? What can be done so pump does not always start at the peak? 
> 
> Thank you in advance 
> 
> On Wed, Nov 26, 2014 at 10:16 PM, <trnsys-users-request at lists.onebuilding.org> wrote:
> 
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>> Today's Topics:
>> 
>> 1. Re: On off time calculator type 980 (Jeff Thornton)
>> 
>> ---------- Forwarded message ----------
>> From: Jeff Thornton <thornton at tess-inc.com>
>> To: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users at lists.onebuilding.org>
>> Cc: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users at lists.onebuilding.org>
>> Date: Wed, 26 Nov 2014 09:22:35 -0600
>> Subject: Re: [TRNSYS-users] On off time calculator type 980
>> Type 24 already accounts for the time step. As Ben suggests, simply connect the same control signal that you use to drive the pump to an integrator as well.
>> 
>> Jeff Thornton
>> TESS
>> 
>> Sent from my iPhone
>> 
>>> On Nov 26, 2014, at 8:31 AM, Ben Heymer <bheymer at gmail.com> wrote:
>>> 
>>> You could integrate the control signal to the pump (should be 0 to 1)
>>> or build your own simple counter using an equation and an integrator,
>>> such as type 24, based on some output value from the pump. For
>>> example:
>>> 
>>> gt(pump_flow_rate,0) * timestep --> integrator
>>> 
>>> Type 24 may already account for the time step, you will have to check.
>>> 
>>> Cheers,
>>> Ben Heymer, PE
>>> 
>>> On Wed, Nov 26, 2014 at 4:07 AM, bridjesh gautam
>>> <bridjeshgautam at gmail.com> wrote:
>>>> Dear. Trnsys users
>>>> I need to find out how many hours my pump was on in the simulation. I found
>>>> type 980 can give me the current running on and off time but not the total
>>>> ,as it starts from zero next time it is on or off. Is there any other way to
>>>> find that out ?
>>>> 
>>>> Thank you
>>>> 
>>>> 
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> 
> -- 
> 
> bridjesh 
> 
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