Time Delay Relays Information
Time delay relays and solid state timers use solid state electronic devices to provide a time delay. They may have displays, pots or other means of operator interface. They may also have electromechanical or solid state outputs.
The number of time ranges on relays and timers are single or multiple:
- Single time ranges may be fixed or programmable.
- Multiple time ranges can be programmed for multiple ranges.
A minimum and maximum time setting must also be specified. Some relays and timers have field selectable time ranges.
Time delay relays and solid state timers can have many timer functions or modes of operation which include:
- Shot and interval
ON-delay timers and OFF-delay timers are two common types of time delay relays and solid state timers.
This type of timer can also be called:
- Delay on make
- Delay on operate
- Operate delay
- Prepurge delay
- Delay on energization
The time delay begins after application of power. At the end of the time delay the contacts open or close. If the contact is normally open (NO) the load energizes at the end of the time delay. If the contact is normally closed (NC) the load de-energizes after the time delay. Removing power resets the time delay and output.
This type of timer is sometimes called:
- Delay on break
- Release delay
- Delay on release
- Postpurge delay
- Delay on de-energization
The timer contacts open or close immediately after power is removed. The preset time delay must elapse before the contacts return to normal position and the load is de-energized.
Power must be applied before and during timing. Re-closing the control switch during the timing resets the time delay. Most reset on loss of power.
One Shot Timers
One shot timers are time delay relays and solid state timers that are also called:
- One shot relay
- Single shot
- Single shot interval
- Single pulse
- Latching relay
- Latching off delay
- Latching delay on de-energization
Contacts change position immediately upon application of power and remain in changed position for the preset time delay. After the time delay, the contacts return to their normal position. Power must be applied before and during timing. Reset occurs when the time delay is completed and the control switch is opened.
Interval timers are time delay relays and solid state timers that are also called:
- On interval
- Pulse shaping
- Bypass timing
- Interval delay
- Delay on energization with instantaneous transfer
Time delay begins when power is applied. The output is energized during time delay and de-energizes at the end of the time delay, and it remains de-energized until power is removed.
This type of relay is also called:
- Duty cycling
- Repeat cycle
- Delay on operate and on release
- ON/OFF dual delay
- Dual-delay energization
Timing function starts with closing of control switch. The load alternately turns on and off at regular intervals until power is removed. Removing power resets the time delay.
A time indicator records and displays elapsed time but performs no output function. Some timers can be programmed to function as a counter as well as timing functions. Time delay relays and solid-state timers are either single function or multi-function devices.
User Interface Specifications
Common user interface specifications for time delay relays and solid state timers include input controls and displays.
- Analog meters
- Simple visual indicators
- Digital numerical displays
Output specifications to consider when selecting time delay relays and solid state timers include the switch type, number of contacts, contact configuration, and pole and throw specifications.
Mountings and power supplies also need to be specified. Operating temperature is an important environmental parameter to consider when selecting time delay relays and solid state timers.
AD 94-24-05 - Time delay relay\short Brothers PLC\sd3-60.
FORD EC2-1 - Nema solid state time delay relays.
MIL-C-83726/21 - Relays, time delay on operate, solid state (Type I).
MIL-PRF-83726 - Relays, hybrid and solid state, time delay, general specification for.
QPL-83726 - Relays, hybrid and solid state, time delay, general specification for.
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