Heater Break Alarm - Honeywell CD3000M-2PH User Manual

User's Manual

6.3 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.
6.3.1 Heater Break Alarm indication
The Heater Break status is displayed with a relay and two leds, as the following table.
SC
(red led)
HB
(yellow led)
: light OFF
: light ON
6.3.2 H.B. Relay
The contact of the H.B. Relay is available on auxiliary terminals.
** 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.
6.3.3 Reset
To reset Heater Break Alarm open RESET contact on terminal 7-8.
CD3000M-2PH from 125A to 700A
18 NC HB relay alarm ** (coil not energized)
19 Common relay HB alarm
20 NO HB relay alarm ** (coil not energized)
SCR OK
SCR short circuit
Laod OK
Load Fault
23
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