NT TIMERS

Brief Specification:

 

Types and Functions:

NT1
Often called 'Delay' or 'Delay-to-on'.
When the supply voltage is switched on timing begins.After the time period has expired the output switches over. It remains in that condition until the supply voltage is removed.

NT2
Often called 'Interval' or 'Delay-to-off'.
When the supply voltage is applied the output device switches immediately. When the time period is complete the output device switches off, remaining in that condition until the supply voltage is removed.

NT34
A cycling timer with equal on to off ratio (1:1).
At the application of the supply voltage the 'off' time begins and the output device is not energised. When the time period has elapsed another begins this time with the output on. The output continues to cycle on and off until the supply is disconnected. This timer is often used to flash warning lights.

NT35
Another cycling timer similar to the NT34 above except that the on period starts when the supply voltage is connected.

NT1P
This timer gives a delay to a fixed pulse of the output device. The fixed pulse is usually no more than 1 second and its width has a repeat accuracy of typically 5%. If the pulse width needs to be of similar accuracy to the main time period or needs to be longer then a TC4 should to be selected. This can be offered with a fixed or variable on period.

NT34P
This is similar to the NT1P except the pulse is repeated cyclically.
Again, the fixed pulse is usually no more than 1 second and its width has a repeat accuracy of typically 5%. If the pulse width needs to be of similar accuracy to the main time period or needs to be longer then a TC34 should to be selected. This can be offered with a fixed or variable on period.

NT22
This timer has the supply permanently connected and has the same action as the NT2, above except that initiation is by a fleeting voltage-free contact or a fleeting voltage pulse rather than the supply. When the initiation trigger is detected the output device switches on for the duration of the time period. If during the timing period another trigger occurs, the output device remains on but the timing begins again. This re-triggering feature can be disabled on request.

NT22H
This timer has the power supply permanently connected. When an initiating contact closure or voltage is detected the output device is switched on but, the timing circuit is held at zero until the initiation disappears. Repeating the initiation zeros the time period again. This timer is often used as a missing pulse detector and can also substitute as a lower cost alternative to the true delay-on-de-energise TDN range.

 

FP TIMERS

This is a new range of microprocessor-controlled timers giving out a fixed, user-specified, pattern of pulses which can be of varying duration. Though mainly used in signalling, alarm and monitoring equipment, variations have been used in electronic water softening equipment.

Brief Specification:

Supply Voltage:	5-48 D.C & 5-250 A.C. (50/60 and 400Hz).
Consumption:	< 1 Watt.
Timing/Pulses:	See FP-ONCE and FP-REP below
Circuit:	Microprocessor.
Accuracy:	Typically 0.01%
Standard Output:	Solid state or relay, depending upon application. User specified.
Operating Temperature:	-20°C to +45°C standard, alternatives available.
Standard Casing:	See Connection Table (alternatives available).

Types and functions

FP-ONCE
Fixed pulse train comprising up to 200 user-specified on/off periods each of which can have an individually specified time. The variation in these individual times can be 250:1. The time ranges from a few micro-seconds to minutes.

The pulse train can be triggered by a voltage or contact.

FP-REP
A repeating fixed pulse train comprising up to 200 user-specified on/off periods each of which can have an individually specified time. The variation in these individual times can be 250:1. The time ranges from a few micro-seconds to minutes.

The pulse train repeats until the supply is disconnected or can be controlled by a voltage or contact.

 

SST & MST TIMERS

These were the original ranges of timers that the company produced at its foundation in 1976. The timing period(s) were then controlled by the single charge or discharge of a capacitor. The ranges have been superseded by more accurate ones but the SST33 and the MST3 remains popular and are, therefore, retained.

Brief Specification:

Supply Voltage:	12-48 D.C & 12-250 A.C. (50/60 and 400Hz).
Consumption:	< 1 Watt.
Circuit:	Relaxation oscillator driving output device. Load does not affect timing.
Time Ranges:	From below 1 Second to 60 Seconds (Customer specified).
Control Range:	See SST33 and MST3 below.
Repeat Accuracy:	Typically 5%
Reset Time:	Better than 100mS - shorter on request.
Standard Output:	See SST33 and MST3 below.
Operating Temperature:	-20°C to +45°C standard, alternatives available.
Standard Casing:	See Connection Table (alternatives available).

Types and functions

SST33
Generally used for hazard or warning light operation and more accurately described as a flasher, this cycling timer has a fixed 1:1 on to off ratio and fixed, client specified, rate. The standard output is solid state - 2 Amps maximum. Other ratings/devices to order.

MST3
Just as the SST33 this timer is generally used for hazard or warning light operation but for more specialised applications. This cycling timer has a variable mark : space (on to off) ratio from 1:5 to 5:1 and a variable, Customer specified, rate. The standard output is solid state - 2 Amps maximum or D.P.C.O. relay contacts rated at 5A/250V~ with a resistive load. Other ratings/devices to order.

 

DST TIMERS

This series comprises a low-cost range of digitally-set, microprocessor-controlled timers. The time is set on a two-decade thumb-wheel switch and, as the internal clock is a crystal high accuracy is maintained over the temperature and timing ranges.

Brief Specification:

Circuit features:	At power-up the microprocessor scans and verifies the setting on the thumb-wheel switches and begins the count-down immediately. Because the setting is loaded in this way, nothing - even the alteration of the set time - can interfere with the time-out. This gives the timer exceptionally good immunity to electrical noise.
Supply Voltage:	12, 24, 48, 110, 230, 440 D.C & A.C. (50/60 and 400Hz).
Consumption:	For A.C. < 1 Watt up to 230V for D.C. < 1 Watt up to 48V.
Time Ranges:	0 to 9.9 Seconds in increments of 0.1 Second. 0 to 99 Seconds in increments of 1 Second. 0 to 9.9 Minutes in increments of 0.1 Minute. 0 to 99 Seconds in increments of 1 Minute. 0 to 9.9 Hours in increments of 0.1 Hour. 0 to 99 Hours in increments of 1 Hour. N.B. The cycling timer DST3 can have a rate setting as an altenative.
Repeat Accuracy:	Typically 0.001% (does not include output device switching time).
Setting Accuracy:	Typically 0.001% (does not include output device switching time).
Reset Time:	Better than 100mS - shorter on request.
Standard Output:	D.P.C.O. Relay with contacts rated at 250V~/5A (resistive load).
Alternative Output:	3.P.C.O. Relay, Solid State or to order.
Operating Temperature:	-20°C to +45°C standard, alternatives available.
Standard Casing:	See Connection Table, alternatives available.

Types and functions

DST1
Often called 'Delay' or 'Delay-to-on'. When the supply voltage is switched on timing begins.After the time period has expired the output switches over. It remains in that condition until the supply voltage is removed.

DST2
Often called 'Interval' or 'Delay-to-off'. When the supply voltage is applied the output device switches immediately. When the time period is complete the output device switches off, remaining in that condition until the supply voltage is removed.

DST3
A cycling timer with equal on to off ratio (1:1). At the application of the supply voltage the 'on' time begins and the output device is energised. When the time period has elapsed another begins this time with the output off. The output continues to cycle on and off until the supply is disconnected. The digital setting can either be time or rate (e.g. cycles per minute).

 

TC TIMERS

This is a range of cycling and associated types of timer with knob or fixed settings of both time periods. The time periods are completely independent and the ratio between 'on' and 'off' periods can be as great as 10,000:1 and vice-versa. Although primarily used as variable timers, the periods can be factory set if desired.

Brief Specification:

TC34
A cycling timer with independantly settable 'on' and 'off' periods. At the application of the supply voltage the 'off' time begins and the output device is not energised. When the time period has elapsed another begins this time with the output on. The output continues to cycle on and off until the supply is disconnected. This timer is often used to flash warning lights.

TC35
Another cycling timer similar to the TC34 above except that the on period starts when the supply voltage is connected.

TC4
This timer gives a variable delay to a variable on period of the output device. After the on period has elapsed the cycle does not repeat but waits to be re-initiated by the supply being disconnected and re-applied.

TC3C
This is similar to the TC35 except that the number of repeat cycles is fixed internally. The number of cycles is user specified.

 

TDN TIMERS

This is a range of true 'delay after de-energisation' timers which do not need a maintaining supply voltage. There are different types each with specific applications. Mainly their use is in safety and monitoring systems, for example to check whether a regularly occurring event is missed.

Brief Specification

Circuit:	Micro-power design single CR electronic delay with integrated voltage trip.
Supply Voltage:	12-48 D.C. and 12- 440 A.C. (50/60 and 400Hz).
Consumption:	For A.C. < 1 Watt up to 230V for D.C. < 1 Watt up to 48V.
Time Ranges:	See individual types.
Control Range:	Maximum : Minimum is 50 : 1 ratio standard or fixed time.
Repeat Accuracy:	Typically 5% .
Reset Time:	Better than 100mS - shorter on request.
Standard Output:	D.P.C.O. Relay with contacts rated at 250V~/5A (resistive load).
Alternative Output:	3.P.C.O. Relay or to order.
Operating Temperature:	-20°C to +45°C standard, alternatives available.
Standard Casing:	See Connection Table, alternatives available.

Types and Functions

TDN1
When a supply voltage is applied, the time period is held in reset and the internal relay energises. This state is maintained until the supply is disconnected when the time period begins. The relay stays energised until the time period expires, when it de-energises. This type does not use a latching relay and is, therefore, fail-safe.

TDN2
This is similar to the TDN1 above except that there is an initial delay from the application of the supply to the relay switching on making it a delay to on/delay to off timer. This can often replace two normal timers.

TDN3
This type uses a latching relay. When a supply voltage is applied, the time period is held in reset and a pulse of current energises the internal relay. The consumption then drops to a low level. This state is maintained until the supply is disconnected when the time period begins. The relay stays energised until the time period expires, when it is de-energised by a pulse of stored energy. It is not suitable for use in fail-safe applications.

 

PROTECTION RELAY

CVT100 The CVT100 is a universal, fast-response voltage/current trip. Its exceptional speed ensures that fault conditions can be acted upon with a minimum of delay. It responds equally to A.C. or D.C. and can be calibrated for D.C., A.C. Peak or A.C. r.m.s. It is available with LED indication and a choice of output states, either energised or de-energised at fault detection. The latter is recommended for fail-safe applications.

The circuit has a sensitivity of 0-100mV into 100 Ohms (0-1mA) and, using standard current transformers or shunt resistors the current trip level can be extended from the basic 1mA range to many hundreds of amps.

Conversely, by using dropper resistors or voltage transformers, the unit will trip on a voltage from 100mV to many kV.

Brief Specification

Supply Voltage:	110/120 and 220/240 A.C. (50/60 and 400Hz). Others A.C. or D.C. to order.
Consumption:	1.5VA.
Standard Output:	D.P.C.O. Relay with contacts rated at 250V~/5A (resistive load).
Sensitivity:	1mA or 100mV into 100 Ohms.
Hysteresis:	1%, alternatives to order.
Accuracy:	Typically 1%
Operating Temperature:	-20°C to +45°C standard, alternatives available.
Standard Casing:	See Connection Table (alternatives available).

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