buzzp
Since you asked, you got it. I am sure this will bring more questions. The reference formula in the Hand Book that is used to calculate balanced load for the 4-wire 3-phase system is given as follows:
Voltage Drop for Lamps = (dc VD)/2
Voltage Drop for motors= 0.866*(dc VD)
And for...
Could any one explain the 0.75 multiplying factor in the following equation. According to the American Electricians' Handbook, when a three-wire system is tapped from a four-wire three-phase system the voltage drop is calculated as follow provided that the effect of inductance is neglected...
dpc
As far as I understand (I am not a mechanical engineer) the water line is constantly under water pressure. The reason for using the fire pump is to make sure that the required discharge pressure at the last sprinkler head is not less than a specified value (I guess 65 PSI). You may want to...
For your info, there are numerous manufacturers that do offer Low voltage listed soft start controllers. To name few of these manufacturers, they are as follows:
1. Firetrol, INC
2. Hubbell Industrial Controls, INC
3. Joslyn Clark Controls, INC
4. Master Control Systems, INC
After reading section 695-7, It states that the maximum starting voltage drop is limited to 15% (regardless of the method of starting). However, my question has to do with the water pressure drop (due to drop in the motor torque). For example if I start a fire pump by a soft start method, my...
Can any mechanical engineer tell me what would be the effect (if any) of low starting voltage of an electric fire pump on the required water pressure? As you may know, the motor torque will drop in a squared amount as the voltage drops. Do you compensate for the drop in the initial water...
