Precision Control Systems 3629C - Manual (Page 5)

MODEL 3629C 1 04/10/2007
DESCRIPTION
The model 3629C is a phase-angle SCR controller which linearly controls, with respect to a command signal, the voltage
applied to a three phase electrical load. The controller can be connected either in-line or inside delta configuration. (See
Figure 23 & Figure 24 .)
The 3629C can be configured to control a 4 wire wye load or with the addition of a 3-phase bridge can control a DC load.
(See Figures 25 & Figure 27 .)
The 3629C controller can accept a 0 to 5Vdc command signal or a potentiometer control. The controller may also be
configured to accept a 4/20mA current loop or a 0-10Vdc command signal . (See Figure 30 .)
The command signal input terminals are electrically isolated from the line and load voltages. The line and load voltages
are isolated from the heatsink on the 50, 80, 120 and 160 Amp units.
FEATURES
1. RMS Current Limit, sets the maximum load current to a desired value. The circuit senses the highest current on the
three loads. This feature is useful for variable resistance loads, or loads that have a low resistance when cold.
2. Current Limit Metering, contacts on command connector ease calibration of the current limit setting. (See Figure 22 .)
3. Over Current Trip, latches the controller off until reset, energizes a relay with form "C" contacts and lights an LED if the
load current exceeds a preset value. These contacts, available on the command connector, may be used to operate
an alarm or other devices. (Contacts are rated 250 Volts at 5 Amps.)
4. Over Current Trip Setting, allows independent adjustment of the over current trip point. Factory set at 175%.
5. Over Current Trip Metering, contacts on command connector ease calibration of the O.C.T. feature. (See Figure 21 .)
6. Top adjust pots, make it possible to calibrate the controller without the necessity of removing the lid.
7. 60 Degree Gate Drive, provides stable operation of the SCR's.
8. A shorted SCR detector, lights an LED and energizes a relay with form "C" contacts if an SCR fails in the shorted
mode. These contacts, with connections available on the command connector, may be used to operate an alarm.
(Contacts are rated 250 Volts at 5 Amps.)
9. Auto Phase Rotation Sensing, The controller is not phase rotation sensitive.
10. Missing cycle detection, if the power is momentarily interrupted, the load voltage is set to zero and then increased to
the desired value at a rate equal to a time constant of approximately 0.2 seconds when power is reapplied.
11. Soft start, causes the controller to increase power to the desired value at a rate equal to a time constant of
approximately 0.2 seconds.
12. Transient protection, a snubber circuit consisting of a non-inductive resistor in series with a capacitor, is connected
in parallel with each SCR pair to protect against high frequency transients. An MOV (metal oxide varistor) is also
connected across each SCR pair to protect against high voltage transients.
13. Choice of Feedback:
A. RMS Voltage feedback (internal) allows the RMS value of the load voltage, to be linear with respect to the
command signal.
B. Average voltage feedback, (factory installed option) allows the average value of the load voltage to be linear with
respect to the command signal. Average voltage feedback is most often used for DC applications.
C. External feedback, may also be selected. (See Figure 18 ). Contact the factory with questions about your
application.