DE-STA-CO VARI-PAK DC CONTROL User Manual

Page 19

WARNING! Do not adjust trimpots with main power on if possible. If adjust-
ments are made with power on, insulated adjustment tools must be used and

safety glasses must be worn. High voltage exists in this control. Electrocution and/or
fire can result if caution is not exercised. Safety Warning on page 2 must be read and
understood before proceeding. Failure to follow the Safety Warning Instructions may
result in electric shock, fire or explosion.

A. Minimum Speed (MIN) – The MIN trimpot is used to set the minimum voltage of the

drive. This sets the minimum speed of the motor. Adjust the MIN trimpot as follows:

1. Rotate Main Potentiometer to minimum speed position (full counterclockwise).

2. Increase setting of MIN trimpot so that motor runs at desired minimum speed.

B. Maximum Speed (MAX) – The MAX trimpot is used to set the maximum voltage of the

drive. Adjust the MAX trimpot as follows:

1. Rotate Main Potentiometer to maximum speed position (full clockwise).

2. Adjust MAX trimpot setting to desired setting of motor speed.

C. Current Limit (CL) – This trimpot is used to set the maximum amount of DC current that

the motor can draw. The amount of DC current determines the amount of motor torque.
The CL trimpot is factory set at 150% of the current established by the jumper J1 selec-
tion. Readjust the CL trimpot as follows:

1. Turn CL trimpot to minimum (CCW) position. Be sure jumper J1 is in proper position

approximately equal to the motor DC ampere rating. (See section III, on page 8.)

2. Set the main potentiometer at approximately 30 – 50% rotation.

3. Wire in a DC ammeter in series with armature lead. Lock shaft of motor.

4. Apply power. Rotate CL trimpot CW until desired CL setting is reached (factory set-

ting is 1.5 times rated motor current).

CAUTION:

1. Adjusting the CL above 150% of motor rating can cause overheating and

demagnetization of some PM motors. Consult motor manufacturer.

2. Do not leave the motor in a locked condition for more than a few seconds since

armature damage may occur.

D. IR Compensation (IR) – The IR Comp circuit is used to stabilize motor speed under vary-

ing loads. Readjust the IR trimpot as follows:

1. Run the motor at approximately 30-50% of rated speed under no load and measure

actual speed.

2. Load the motor to rated current. Rotate IR trimpot so that the loaded speed is the

same as the unloaded speed measured in 1.

Control is now compensated so that minimal speed change will occur over a wide
range of motor load. (Note: Too much IR Comp will cause unstable [oscillatory]
operation.)

XI. FUNCTION INDICATOR LAMPS

The control contains three LED Indicator Lamps on the front cover that reflect its operational
status.

A. Power On Indicator (ON) – This lamp will glow GREEN when the AC line is connected

to the control.

B. Stop Indicator (STOP) – This lamp will glow YELLOW when the control is placed in the

STOP mode with the Run-Jog/Stop Switch or logic contact.