HP (Hewlett-Packard) 2995 Power Supply User Manual


 
15
DEC/B: Deceleration (with 60 Hz or 120 Hz configuration)
The DEC/B trim pot sets the time it will take the
motor to reach zero speed from an initial full speed
setting. The trim pot is factory set to approximately
1.5 seconds. Adjust the trim pot as required for the
application.
Application Note: On applications with high inertial
loads, the deceleration may automatically increase
in time. This will slow down the rate of speed
decrease to prevent the DC bus voltage from rising
to the overvoltage trip point. This function is called regeneration protection.
It is recommended that for very high inertial loads that both the ACC and
DEC/B trim pots be set to a minimum of 10 seconds.
DEC/B: Boost (with 50 Hz configuration)
When the control is set for 50 Hz motors, the DEC/B
trim pot becomes Adjustable Boost. Most 60 Hz
motors conforming to NEMA standards can operate
from a preset volts/Hz curve. 50 Hz motors generally
differ widely in their characteristics. Therefore, it is
necessary to have Adjustable Boost to obtain
maximum motor performance. Since the boost trim
pot was the deceleration trim pot in the 60 Hz mode, it
will take on the prior setting of the DEC/B trim pot.
In order for the 50 Hz motor to run properly, the boost
must be adjusted. If the application does not require full torque below 10
Hz, the boost trim pot can be conservatively set at 8% (9 o’clock position).
If more precise speed regulation is required due to varying load, the boost
can be set as follows.
1. Place an AC analog RMS ammeter in series with one motor lead
(Generally, digital or clamp-on meters do not yield accurate readings).
2. Run the motor unloaded* at approximately 4 Hz (or 120 RPM). (*Note:
An unloaded motor with excessive boost will draw more current than a
partially loaded motor.)
3. Turn up boost until the ammeter reaches the nameplate rating.
4. Using the main speed potentiometer, slowly adjust motor speed over a
0 – 15 Hz (0 – 450 RPM) range. If motor current exceeds nameplate
rating, lower boost setting.
CAUTION
To avoid motor winding overheating and failure, do not over
boost motor.
DEC
10.0
SECONDS
18.51.5
(60Hz ONLY)
20.00.3
17.03.0
DEC/B
18
50 Hz
% BOOST
26
306
10