A
We are using LTi PMII+ drives for pitching of wind turbines blade. we are facing failure of Brake resistors leading to dc link over voltages.
LTi MOOG Drive PMII+
rating
Voltage: 3*400V
Current: 40A
Power rating of drive: 22kW
Chopper activation when DC Link voltage >650V
Over voltage error when DC Link voltage >=700V
Brake resistor: 300W, 20Ohms
We are using pitch drive with 7.5kW motor to pitch the blades.
Rated speed of motor 1445rpm
Rated current: 27A
eff: 0.86
max deceleration: 20deg/sec2, deceleration time: 0.4sec,
at max speed of 8 deg/sec (blades) where speed of motor is 1516 rpm of motor, taking into consideration GB ratio
max Braking duty cycle = 1.83%
We are facing brake resistor failure in this drive due to which we get over voltages on DC link and the entire system (Turbine) trip. I need help to understand what can be reason for the failure of the resistor.
I have calculated average brake power Pavg = 1072.57W. As per datasheet of Resistor we can load it 20 time *300W (rated power) = 6000W.
So required Brake resistor = 1072.57W/20 = 53W and we have used 300W Resistor.
LTi MOOG Drive PMII+
rating
Voltage: 3*400V
Current: 40A
Power rating of drive: 22kW
Chopper activation when DC Link voltage >650V
Over voltage error when DC Link voltage >=700V
Brake resistor: 300W, 20Ohms
We are using pitch drive with 7.5kW motor to pitch the blades.
Rated speed of motor 1445rpm
Rated current: 27A
eff: 0.86
max deceleration: 20deg/sec2, deceleration time: 0.4sec,
at max speed of 8 deg/sec (blades) where speed of motor is 1516 rpm of motor, taking into consideration GB ratio
max Braking duty cycle = 1.83%
We are facing brake resistor failure in this drive due to which we get over voltages on DC link and the entire system (Turbine) trip. I need help to understand what can be reason for the failure of the resistor.
I have calculated average brake power Pavg = 1072.57W. As per datasheet of Resistor we can load it 20 time *300W (rated power) = 6000W.
So required Brake resistor = 1072.57W/20 = 53W and we have used 300W Resistor.