9
'CL' Trimpot
The Current Limit (CL) trimpot is set to 4.8 amps RMS from the factory. A CW rotation of the CL
trimpot will increase the CL set point. A CCW rotation of the trimpot will decrease the CL set point.
CL should typically be set to 150% of the rated motor phase current. To set up CL for other motors,
place a RMS current meter in series with one of the motor phases. Load the motor to 150% of
rated motor phase current and gradually decrease the CL trimpot setting until the red Fault LED
first begins to flash. Cease any further trimpot change, AND release the motor load.
The EZ VFD® offers Multi-Level Current Limit (MCL)™, an advanced level of drive and motor
protection. MCL includes both PEAK and SUSTAINED OVERLOAD monitoring and when exceeded,
will shut the drive output off. PEAK monitoring (factory set) is cycle by cycle protection against
rapid motor current surges. SUSTAINED OVERLOAD monitors continuous motor current (set by
the CL trimpot) and if the setting is exceeding for 2 seconds, the drive output will shut off.
The red Fault LED (on circuit board of chassis / cover of enclosed model) will illuminate steady
when the drive is in a Current Limit state of either description. The green Power LED will remain
illuminated steady. There are three ways to reset the drive:
1) Open the ‘Run’ jumper (P9-9 to P9-8) until the red Fault LED turns off
2) Turn main Speedpot full CCW (if set at less than 50%, will need to turn above 50%, then full CCW)
3) If with either method the green Power LED cycles off, then on again steady, the drive may be
operated again
4) If the CL fault is the third occurrence while power has remained on, to reset the drive it will be
necessary to cycle power to the drive
Repeated CL shutdowns are an indication that the system should be evaluated further by a
qualified control technician.
'BOOST' Trimpot
The BOOST trimpot allows the the motor to overcome sluggish response at low speed starts
or high' startup loads by boosting the output. To increase the boost setting rotate the BOOST
trimpot CW. To decrease the boost setting rotate the BOOST trimpot CCW.
To determine if boost is required for your application, use the following setup method. With
a normal motor load applied, slowly turn the MIN trimpot CW until you reach 30% rotation. If your
motor has started up you will likely not need to adjust the BOOST trimpot. However if your motor
hasn't started then slowly increase the BOOST trimpot until your motor starts to turn. Return the
MIN setting to 0 (full CCW) and repeat the test to make sure the motor starts at low speeds.
Note: Running a motor continuously at low speeds with Boost turned up may cause some
motors to over heat.
'BRAKE' Trimpot
Brake is a DC Injection Brake function when the motor speed is 0 Hz. This function can be
used to hold a motor position in between speed commands. To activate Brake a contact must be
closed from the BRAKE terminal on P9-11 to circuit Common on P9-8. A CW trimpot rotation will
increase the level of DC injection braking. A CCW trimpot rotation will lower the level of braking.
If Brake is activated while the motor is running then the motor will reduce to 0 speed at the rate of
the DECEL trimpot setting. When the motor has stopped, the DC Injection Braking will be applied
at a level determined by the trimpot setting.
Note: When the BRAKE trimpot is at full CCW the Brake function is fully disabled even if the BRAKE
to COM contact has been closed.
CAUTION: Although the brake function can be limited by your CL setting, using Brake even at
lower levels to hold a motor at 0 speed for extended periods of time can cause excessive heating
of the motor.
