It is common (Not alway's the case) for the service brake to be fed from the motor stator feed. I.E. the dead side of the motor directional contactors - In this configuration the brake cannot be lifted unless you have power going to the motors.
This could be backed up by some form of rotor...
The resistor is left in circuit so that the torque speed curve for induction generating is flatter and broader, so if the load has a tendency to want run away it will stay within the peak torque of the motor. If the resistor is shorted out, it is (remotely) possible for the motor to accelerate...
Hello James
Can you tell me what what kind of Opotor system is fitted, Is it controlled via voltage relays connected across two of the rotor phases or some kind of frequency relays across two of the rotor phases.
This type of system is generally designed so that at full load the hoist will...
HW Desaturation generally points to the supply being removed, then reapplied before the drive bus decays, and so could point to a supply problem. Do you have line contactors in the supply to the drive, if so check the contact faces, i have experienced some wierd kind of pitting on a baldor drive...
When the original fault occured,how was power removed from the drive. Was the drive stopped in the correct manner or was the input power disconnected from the drive ?.
It sounds to me like some kind of bus over voltage may have occured.
Did they kill the drive before the load had come to rest...
Their are two types of Safety Harness attachment point.
Fall restraint :- prevents you from stepping over an edge.
Fall Arrest :- Catches you when you fall.
A fall restraint attachment point need only be strong enough to resist a person from reaching the open edge and so may be adjacent...
An E-stop is generally used to bring a machine to a halt as quickly as possible and is not intended to provide a full isolation and immobilisation from all sources of energy.
An E-Stop cannot be expected to remove all sources of energy as this may not be the safe thing to do in every foreseeable...
Yes and no !!
Im trying to figure out why the motor manufacturer ( I think it was GEC The motor was an MDX frame i think ) advised me to swap the field connections back and then swap the armature connections for motor reversal when i had the problem i described earlier. It worked.
The...
Surface corrosion should be picked up as part of a visual inspection, which should lead on to a closer inspection during the detailed inspection. I would have thought that the surface rust in itself is not a problem so long as the corrotion has not penetrated the metal so far as to make the...
Edison123
"By reversing the shunt field polarity, both the polarity of shunt field coils and the direction of rotation change"
I Agree
"thereby maintaining the relationship between interpole polarity and the shunt field polarity.
I Disagree - Draw a simple 2 pole (pairs) motor on...
Edison123
Reversing the shunt field polarity will reverse the direction i agree, but it will not reverse the polarity of the interpoles as these are in series with the armature. Interpoles are wound and placed so that each interpole has the same magnetic polarity as the main pole ahead of it...
My 2003 CompEx toolbox guide quotes " Clearance between bare conducting parts or terminals of separate intrinsically safe circuits is to be no less that 6mm for all voltages up to 90 Volts peak.
Sorry your right i'm wrong the 50mm is between the parts stated above but not to earth, the only mention of clearances to earth are:- Quote " The clearance distance from bare conducting parts of external conductors connected to a terminal, to any earthed ( or other conducting parts )shall...
yes this is a requirement of EN 50020 IEC 60079-3. These clearances also apply to the spacing between the AC power terminals and the 'i s' output terminals of a module and to the spacing on a terminal rail between 'i s' circuits and any other power terminals.
regards AC
