Thyristor Firing Mode - Honeywell CD3000M User Manual

User's Manual

7. Thyristor firing mode

ZERO CROSSING
VOLTAGE SUPPLY (V)
LOAD VOLTAGE (V)
SSR from controller
VOLTAGE SUPPLY (V)
ON OFF
SOFT
VOLTAGE SUPPLY
START
LOAD VOLTAGE
FIRING SIGNAL
CD3000M-1PH from 125A to 700A
20%
50%
70%
100%
20%
VOLTAGE SUPPLY (V)
50%
70%
100%
7.1 Zero Crossing (ZC)
ZC firing mode is used with Logic Output from
temperature controllers and the Thyristor
operates like a contactor. The Cycle time is
performed by
minimizes interferences because the Thyristor
unit switches ON-OFF at zero voltage.
7.2 Single Cycle (SC)
It's the fastest
method in respect to the power demand from
a temperature controller or an external signal.
At 50% input signal is one cycle ON and one
cycle OFF. At 75% is 3 cycles ON-one cycle
OFF. If power demand is 76% the unit
performs like for 75% but every time that
switches ON the microprocessor divides 76/75
and memorizes the ratio and when the sum of
rest is one the unit deliveries one cycle more
to the load. With this firing is necessary to
have analog input.
7.3 Burst Firing (BF)
This firing performed in Digital mode in
Honeywell Thyristor unit gives a lot of
advantages because switches Thyristor at
zero voltage crossing without EMC
interferences. Analog input is necessary for
BF and can be decided how many complete
cycles we want at 50% of power demand.
This value can be implemented from 1 to 255
complete cycles doing the firing less or more
fast. When 1 is setted the firing name
becomes Single Cycle (see above).
7.4 Soft Start + Burst Firing
(S + BF)
This is an additional feature to Burst Firing.
The unit start in phase angle mode with a
ramp starting from zero up to full voltage in a
presetted and Adjustable time. After which
the rest of ON period will be at full
conduction. This firing S+BF is used to switch
ON small inductive loads to avoid inrush surge
current and to reduce at minimum electrical
interferences.
29
Honeywell
temperature controller.
zero crossing switching
www.honeywell.com/imc
ZC