User’s Manual
CD3000M-1PH from 125A to 700A
Honeywell
25
www.honeywell.com/imc
6.2 Heater Break Alarm
Heater Break Alarm is a microprocessor based circuit to diagnose partial or total load failure and
short circuit on SCR and fuses failure.
The contacts of these relays are intented to be connected only to a Class 2 Power Supply or
a Limited Voltage Limited Current source of supply with Class 2 characteristics.
•
discrimination better than 20%;
•
latching alarm plus reset.;
•
relay output 0.5A at 125VAC.
H.B. circuit read load current via a current transformer 100-250/0.05 or 400-900/0.05 depending on
the thyristor unit size. The current trasformers are internal to the unit..
Minimum current readable is 10% fo nominal current of the thyristor unit.
6.2.1 Heater Break Alarm indication
The Heater Break status is displayed with a relay and two leds, as the following table.
SC
(red led)
SCR OK
SCR short circuit
HB
(yellow led)
Laod OK
Load Fault
: light OFF
: light ON
6.2.2 H.B. Relay
The contact of the H.B. Relay is available on auxiliary terminals.
18
NC HB relay alarm ** (coil not energized)
19
Common relay HB alarm
20
NO HB relay alarm ** (coil not energized)
** In alarm condition or without auxiliary voltage the relay coil is not energized. In
normal condition (no alarm) the relay coil is energized.
Switch cut-off capacity of the contact relay output is 0.5A at 125VAC.
6.2.3 Reset
To reset Heater Break Alarm open RESET contact on terminal 7-8.
