HP 2995 - Manual (Page 16)

16
CL: Current Limit with I 2 t Shutdown
The CL trim pot is used to set the maximum motor
current that occurs in a stalled condition. The CL
trim pot is factory set to approximately 160% of full
control rating (3.8 amps). The CL trim pot can be
readjusted as required.
The current limit also contains an I
2 t trip function.
The control will trip according to a predetermined
current versus time function. The trip curve is
directly related to the CL set point and can be changed with the CL trim
pot. The current limit with I
2 t shutdown is designed to provide motor
overload protection. Readjust the CL trim pot so that it is set to 160% of
full rated motor current as follows.
1. Connect an AC ammeter in series with one motor phase.
2. Lock motor shaft and quickly adjust desired locked rotor motor current
using CL trim pot. Note: This adjustment must be made within 60
seconds or I
2 t trip will occur.
Example: A ½ HP motor has a full load current of 1.8 amps. Set the CL
trim pot to 1.8 X 160% = 2.9 amps.
Percent of CL
Setpoint
Trip Time
(Minutes) Control Rating
(%)
Motor Current
(Amps/Phase)
100 .1 (6 sec) 160 3.8
88 .8 140 3.4
75 30 120 2.9
63
4 100 2.4
COMP: Slip Compensation
The COMP trim pot is used to maintain set motor speed under varying
loads. The factory setting of 1.5 volts/Hz/amp provides excellent speed
regulation for most motors. The COMP trim pot can be adjusted for
specific applications as required.
1. Wire an AC ammeter in series with one motor
phase.
2. Run motor and set unloaded speed to
approximately 50% speed. Using a tachometer,
record unloaded speed.
3. Load motor to rated motor current (AC amps)
4. Adjust COMP trim pot so that loaded RPM is
equal to unloaded RPM.
5. Motor is now compensated.