Number of Start per Hour
Number of Start per Hour
(OP)
hi! folks
I would like to know if there is a standard calculation of Number of Start per hour of a motor? could it was affected by the number of poles, duty cycle, applied voltage, etc?
How about if the machine was fitted to electrical braking modes such as plugging, dynamic braking, or frequent reverse-stop modes? how can we apply the Number of start per hour regulations?
Anyone could specify on AC and DC machines. Much better if anyone could provide substantial reference and or manuals on calculations).
thanks,
fbjavier





RE: Number of Start per Hour
http://www.joliet-equipment.com/allowable_starts.htm
Columns A and B give max number of starts per hour on average over life of the motor to prevent excessive long-term degradation.
Column C gives miniumum rest time between starts to prevent short-term degradation from insufficient cooling between starts.
The tables are dependent on speed and horsepower as expected. Regarding the minimum time between starts, one thing which they don't give is the status run or off between starts which makes a difference. Machine will cool faster if running for most of the time between starts.
NEMA MG-1 also has some words about 2 starts cold or one start hot. For large motors, we ask the OEM to provide us starting duty specific to each motor.
RE: Number of Start per Hour
RE: Number of Start per Hour
Is there something to suggest a certain coast down time is built into the standard NEMA MG10 limits? As I mentioned I feel there is lacking any info about whether time between starts is run or idle and coast-down would play a role as well.
RE: Number of Start per Hour
Visit
http://www.reliance.com/mtr/flaclcmn.htm
for motor plugging duty at the end