Loss of Mains Relay – type LMR-111D0 pages

DEIF A/S
Application
The loss of mains relay type LMR-111D forms part of a
complete DEIF series of relays for protection and
control of generators.
This relay is applied for protection of synchronous
generators, running in parallel with the mains.
A mains failure will be detected, provided a disconnection
at an arbitrary point of the network results in a swift
change of the generator frequency (vector shift). An
opening signal is then transmitted to the mains circuit
breaker, and the generator will thus be protected
against damages caused by an automatic reconnection
to the high-voltage network.
The LMR-111D will on the other hand not detect the
normal relatively slow and acceptable changes of the
frequency of the network (the mains).
Furthermore, separation of a generator from the mains
in case of mains failure is also stipulated as a condition
in most national rules for connection of synchronous
generators to the mains. Regarding Great Britain, see
Engineering Recommendation G59.
Measuring principle
The relay supervises the angular velocity of the phases
of the mains. The velocity is supervised by comparing
the times for the latest two full cycles with the times for
the full cycles of the previous 4th and 5th period.
After 5 periods have passed (after connection to the
mains) the relay will thus have performed the first
measurement. After this the LMR-111D will within one
period detect a vector shift.
This method of measurement (comparing periods 1 and
2 with periods 4 and 5) ensures correct detection of a
vector shift occurring very close to the zero crossing of
the AC voltage.
If the difference between the measurements exceeds
the set point, the output is activated. Within 30 ms
(inclusive of contact delay), an opening signal is transmitted
to mains circuit breaker, and the LED marked
"MAINS FAIL" is lit. The set point value is set on the
front of the relay by means of a potentiometer marked
“SENS”.
The LMR-111D is provided with 1 reset input connected
to contacts to the generator circuit breaker and
to the mains circuit breaker. These 2 contacts should
close when their respective circuit breaker is opened.
When the RESET (22-23) is activated, the LMR-111D
will not detect a possible mains failure. This function
ensures that the relay is only active when both circuit
breakers are closed and the generator thus is running
in parallel with the mains.
On receipt of a reset signal (transmitted by the mains
circuit breaker auxiliary contact during opening of its
circuit breaker), an internal timer is started. When this
expires (after 2 s), the opening signal to the mains
circuit breaker is cancelled, and the LED “MAINS FAIL”
is switched off.
The LMR-111D is provided with an adjustable initialising
timer, which is activated on cancellation of the
reset signal (closing of circuit breakers). When this
timer expires, the LMR-111D is activated and the LED
“Supervision” is lit. The time delay is set on the front of
the relay by means of the potentiometer "Delay".
Relay outputs
The LMR-111D is provided with 2 output contacts (with
common set points), either normally energised or
normally de-energised. The contacts may be set to
open or to close on activation.
Normally energised contact
Recommended for warning and alarm purposes. In
case of an auxiliary supply drop-out, the contact is
immediately activated.
Normally de-energised contact
Recommended for regulating and control purposes. An
auxiliary supply failure will not result in an unwanted
activation of the contact.
Power-up circuit
The relays are provided with a 200 ms power-up
circuit, ensuring the correct function of the relay on
connection of the auxiliary voltage.
Note: Normally energised contacts are not activated
(contact does not open/close) until 200 ms
after connection of the auxiliary voltage.
ANSI code 78 Loss of mains relay
Type LMR-111D uni-line
4921240214D
• Detection of vector shift
• Mains disconnection on mains failure
• Ensures no asynchronous reconnection
• LED indication of fault condition
• LED indication for activated relay
• 35 mm DIN rail or base mounting LMR-111D