Surge suppression is required across
inductive loads to guard against premature
relay failure. Figure 1 illustrates diode
surge suppression for a DC load. The
diode's operating (peak inverse) voltage
should exceed the load's supply voltage
by at least 50% and should have a current
rating of at least one ampere.
Figure 2 shows surge suppression for an
AC load, using an MOV (Metal Oxide
Varistor) and a capacitor. The breakdown
voltage ratings of both the MOV and the
capacitor must exceed the peak AC
voltage.
With normal sine-wave power, PEAK =
1.414 x RMS voltage. For 115 VAC power
a 200 volt peak rating is recommended.
WARRANTY
The Mighty Module Series of products
carry a limited warranty of 10+5 years. In
the event of a failure due to defective
material or workmanship, during the 10
year period, the unit will be repaired or
replaced at no charge. For a period of 5
years after the initial 10 year warranty,
the unit will be repaired, if possible, for a
cost of 10% of the original purchased
price.
Relays are not covered by the warranty.
MOUNTING
MM1820, MM1821 and MM1824 are
designed to plug into a standard 11-pin
relay socket. (MP011) is an 11-pin socket
suitable for mounting on a flat surface or
in a piece of PVC track, (TRK48).
Spring holddown clips are available for
installations where vibration may be a
problem. Use part number (CLP1) with
MM1820, (CLP2) with MM1821 or MM1824.
SPECIFICATIONS
INPUT POTENTIOMETER
RESISTANCE
any value from 100 ohms
to 100 kilohms
INPUT SPAN ADJUSTMENT
70% to 100% of pot rotation
INPUT OFFSET ADJUSTMENT
0 to 25% of pot rotation
INPUT IMPEDANCE
>10 megohms
EXCITATION
1 V, 10 mA max load
SETPOINT
each alarm 0 to 100% of span
DEADBAND
Standard
fixed 0.5% of span
(Option A)
0.5% to 100% of span
(Option D)
Latching. Interrupt power to reset.
RESPONSE TIME
20 ms typical
ACCURACY
±0.1% of span
COMMON MODE REJECTION
120 dB, DC to 60 Hz
RELAY CONTACTS
(spdt)
Resistive Load:
5 A max, 150 W max,
240 VAC, 30 VDC max
Inductive Load:
1
/
8
HP max at
120/240 VAC
TRANSISTOR OUTPUT
(Option V)
open-collector, sink 100 mA,
30 V supply max
OPERATING TEMPERATURE
14°F to 140°F / -10°C to 60°C
TEMPERATURE STABILITY
±0.02% of span/°C max
POWER
115 VAC ±10%, 50 or 60 HZ
(2.5 W max)
230 VAC ±10%, 50 or 60 Hz
(2.5 W max)
(DC Power Option)
24 VDC
(limits 21 VDC to 32 VDC)
(2.5 W max)
Isolation, DC power supply
to input common: 10 megohms
Specifications are subject to change without notice. © 2008 Wilkerson Instrument Co., Inc. DWG#101035B 3/15
DIMENSIONS
INCHES [mm]
MM1820
MM1821 and MM1824
3
4
