CAUTION
Do not connect the terminals to an alternating current supply. Alternating current will destroy the wire break detection.
CAUTION
The relay with wire break detection uses a small, constant current for wire break detection. This current can activate small
relays, and cannot be turned off.
INFO
Remember to install the freewheeling diode (
). This diode prevents a sudden voltage spike across the inductive
load when the voltage source is removed.
Checking the relay size
The wire break detection current leak does not activate the relay if this formula is true:
V
release
> (V
supply
- 4.5 V) / (3900 Ω + R
coil
) × R
coil
V
release
The release voltage for the relay (see the relay's data sheet).
V
supply
The supply voltage that the relay is connected to (12 or 24 V).
R
coil
The relay coil resistance (see the relay's data sheet).
CAUTION
This formula does not include a safety factor.
If the calculation shows that the relay is too small, use a relay with a higher release voltage and/or a smaller coil resistance.
Relay coil resistance calculation example 1
For a 24 V supply, a relay with a 7.5 V release voltage and a 630 Ω coil is proposed.
The right side of the equation is then (24 V - 4.5 V) / (3900 Ω + 630 Ω) × 630 Ω = 2.7 V.
INSTALLATION INSTRUCTIONS 4189340909I UK Page 79 of 144
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